So, what should we call a couple sects, here (I'm bad at coming up with names)

FROM THE MIMIR:

The Planar Order
On Athas, there is, or was at least, a secretive and shadowy order that desired to control the use of all psionics on Athas. A few of their cutters managed to make their way to the Outer Planes and began to do something similar until they realized that things were too different in the Outer Planes to use their old secretive methods: for the first part, psionicists were few and far between, and a cutter that made it to the typical level where they would attract the attention of the Athasian order was much fewer because of the lack of education about psionics. They've managed to salvage much of their original blunders, they still wander the planes searching for powerful psionicists to recruit into their ranks. Recently, Cheik Ghear of the School of the Mind has attracted their attentions

The Order
(Sect)

Sect Philosophy: The control of the Planes stems from the control of the mind. Each individual's mind brims with psychic potential, but most of them are unaware of their powers. Those that are become powerful cutters in the planes, tipping the scale of The Balance too far in one way or another. The Balance must be maintained in all things, to be sure. Should the Balance require murder, than the Balance requires murder. All will join to uphold the Balance, or they shall be considered an Enemy of The Order.

Primary Plane of Influence: The Outlands, the plane of Balance in all things, is the primary plane of influence for these cutters. They maintain no stronghold or hold any official meetings, but many of them can be found throughout the gatetowns of the Plane, attempting to keep them on the Outlands in order to ensure that no one plane becomes too powerful or too large.

Allies and Enemies: The neutral bent of The Order attracts them to the teachings of the Ciphers, although their methods cause any real support from the faction to be withheld. The focus on the mind and the self attracts factions such as The Sign of One and the Fated to the side of The Order as well, but neither actually acknowledges the group's existence, mostly in part because nobody's really aware that they do or do not exist.

Eligibility Requirements: The Order actively recruits any psionicist of True Neutral alignment that reaches 12th level. Other cutters just can't see the importance of The Balance or they just aren't powerful enough to enforce it. To recruit a new psionicist into The Order, they approach them with the offer to "Join or die." Should the invited psionicist refuse, they will be killed so that The Order does not gain publicity. If they accept the offer, they join The Order and begin to serve the cause of The Balance actively.

Special Benefits: The Order is a group of cutters that share a vast knowledge among each other. Any member of The Order can usually kind the guidance of another member in order to be taught psionic power keys for various planes and the like.

Special Hindrances: A member of The Order is a member for life; those attempting to leave it will be hunted down and killed. Also, while a member, the psionicist must constantly think of The Balance before all else; severely aligned actions earn first a reprimand, then execution.

It should come as no surprise that the current head of The Order (that is, the blood that's served The Order for the longest) is a rilmani aurumach, who sought a position in the order after mastering psionic powers expressly for the purpose of joining The Order. Since his becoming the leader of The Order, he's preserved The Balance with a fanatical devotion. To him, the Balance is more important than The Order. This has caused a few disgruntled member of The Order who see themselves simply as a pawn in the schemes of an aurumach, who cares little for the control of psionics across the Outer Planes. The most vocal of these dissidents is Xelran (Pl/♂ githzerai/Psi12 (Psychokinetics)/The Order/N), a githzerai blood who believes that The Order should take steps to begin to regulate the use of psionics across the planes as their organization on Athas believed. Nothing's happened yet, but Xelran ain't likely to stay quiet forever.

The School of the Mind
The School of the Mind in the Lady's Ward is Sigil's premier school of the mind. However, the school receives little attention or publicity because it is not connected in any way to the factions, which also caused the death of the Guild of Psionicists about two hundred years ago. The school has on average twenty students at any one time, each of which is eager to learn about their minds and how it can affect the multiverse. Most of these are wide-eyed Signers that drop out after a few weeks. Still, some manage to stick with it and gain the basics of harnessing their mental energies.
The school is run by a dispassionate human named Cheik, who seeks to enlighten the boors of Sigil as to the true nature of the mind. Once a member of the Ghear family of the Lady's Ward, he has since disowned his family to embrace the study of his mind. Entrance to the School is only available after a screening by Cheik himself, where he determines whether or not the applicant has the potential to harness their mind. Of course, it costs fifty gold just for a screening, and five hundred for a beginner's course in the powers of the mind. Cheik's vision of enlightenment is restricted by his lack of money.

Cheik Ghear
Male human planar
13th level Psionicist (Psychometabolist)
True Neutral

Str: 8 Int: 15 hp: 65
Dex: 11 Wis: 16 THAC0: 14
Con: 17 Cha: 7 AC: 8 (leather armor)

PSPs: 155
Psionic Abilities:
Psychometabolism:
Sciences: animal affinity (vaath), energy containment, metamorphosis, nerve manipulation
Devotions: accelerate, adrenaline control, body equilibrium, cause sleep, cell adjustment, cause decay, chameleon power, enhanced strength, reduction
Psychoportation:
Sciences: teleport
Devotions: dimension door, astral projection
Metapsionics:
Devotions: receptacle
Telepathy:
Sciences: mindlink
Devotions: contact, ego whip, ESP, mind bar

Equipment: ten receptacles, each holding 20 PSPs; amulet of mind shielding, Sigilian long sword +3 (his inheritance)

Cheik Ghear was born in Sigil to wealth beyond the lowest Hiver's imagination. Born to the Ghear family, a wealthy family of merchants and scholars, he was guaranteed a comfortable life of opulence. That is, until he met a withered old githzerai on the streets of the Lady's Ward while he was on a walk. The githzerai would not move aside, despite Cheik's orders. Then, the githzerai touched Cheik's mind, and Cheik could feel the power in the old man. He could feel the power in his own mind that had lain dormant for his entire life before. The githzerai then vanished from Cheik's sight, never to be seen again. Cheik spent the next ten years advancing himself, reading all the books in the libraries of Sigil about the odd powers of the mind. Once thirty years old, he divorced himself from his family and founded The School of the Mind with what money he had (which was quite a bit), dedicated to teaching the people of Sigil about the power that the mind has.
As the head teacher at the School of the Mind, he teaches Basic Psionic Teaching and Psychometabolism: Strength Through Change. The other teachers that he has working for him are the telepath Avia Windhair (Pl/♀ genasi [air]/Ps10/NG) and the mentally unstable psychokinetic tiefling Verik (Pl/♂ tiefling/Ps9/NE), both of whom hate each other with a burning passion. Other teachers work for him, but most of them don't stay long. Currently, he's looking for someone to teach the discipline of psychoportation, as he has only a basic knowledge of it.

Courses that the School of the Mind offers are as follows:

Course: Cost* Teacher:
Basic Psionic Focusing: 500 gp Master Cheik
Psychic Lore: What Has Come Before. 500 gp Master Verik
Meditation: To Know of Oneself Is To Know All 500 gp Master Avia Windhair
Basic Combat: Speak Softly and Carry a Big Sword. 500 gp Master Verik
Clairsentience: Knowledge Through Introspection 1000 gp Master Avia Windhair
Psychokinetics: Movement Through Force of Will 1000 gp Master Verik
Psychometabolism: Strength through Change 1000 gp Master Cheik
Psychoportation: Giving Them "The Laugh"** 1000 gp Master Cheik
Telepathy: Respect Through Fear 1000 gp Master Avia Windhair

* Non-refundable. We at the school apologize for those applicants who fail to harness the full potential of their minds, but refunds are not a part of policy.
**The title "Giving Them 'The Laugh'" in no way implies that the School of the Mind encourages breaking the Laws of Her Serenity, The Lady of Pain. In fact, the School of the Mind is a regular supporter of Her Serenity and Her Most Gracious Servants the Harmonium, Fraternity of Order, and the Mercykillers.

Current Chant: Recently, Cheik has been receiving visions in his sleep from a being of extreme psionic power. Cheik feels like his has either been contacted by a force more powerful than the solar or he is going slowly insane. The visions involve him being chased by lions and other animals through Krigala, in the Beastlands, until he finally reaches an oasis in twilight, above which hovers a silvery being of pure light, who tries to communicate with him psionically, but Cheik finds himself unable to understand the words in his head. The dreams are driving him slowly mad, whatever their intent may be. (for more information, see Trinius below)

Trinius
The Outer Planes owe much to the Prime World of Athas in the art of psionics; many of the most powerful psionicists that have blazed new paths in the way that psionics is thought about in the Outer Planes. Trinius is an advanced being from Athas, known as an avangion, possibly the first of his kind. He lives in the Beastlands on the shadowy layer of Brux, first outlined in A (More) Complete Guide to the Outer Planes.

Trinius
Male prime avangion
30th level preserver/psionicist
Neutral Good

Str: 6 Int: 20 hp: 123
Dex: 14 Wis: 23 THAC0: 7
Con: 17 Cha: 20 AC: -6

PSPs: 419
Psionic Abilities:

Clairsentience:
Sciences: aura sight
Devotions: all-round vision, danger sense, see magic

Psychokinesis:
Sciences: detonate, telekinesis;
Devotions: cryokinesis, deflect, inertial barrier, molecular agitation

Psychometabolism:
Sciences: nerve manipulation, regenerate
Devotions: accelerate, cell adjustment, double pain, ectoplasmic form, heightened senses, mind over body

Psychoportation:
Sciences: teleport, time travel
Devotions: blink, dimension door, time duplicate, time shift, phase, time dilation

Telepathy:
Sciences: domination, ejection, mindflame, mindlink, probe, psionic blast, tower of iron will
Devotions: attraction, aversion, awe, contact, ego whip, ESP, id insinuation, intellect fortress, mental barrier, mind blank, mind thrust, psychic messenger, psychic crush, repugnance, send thoughts, synaptic static, thought shield, truthear

Metapsionics:
Sciences: appraise, empower
Devotions: gird, magnify, probability manipulation, splice

Special: tongues, know alignment, ESP, detect lie (all of the previous always active); 80% magic resistance, hit only by weapons of +5 or better enchantment, MV Fl 60 (A)
His radius of light, which extents to a 200' radius, has the following permanent effects within it.

• globe of invulnerability
• protection from evil
• dispels all magical darkness
• acts as ray of enfeeblement to all evil creatures

Spells: (7/7/7/7/7/7/7/6/6/4) 1: Read Magic, Hypnotism, Charm Person, Audible Glamour, Sleep, Phantasmal Forces, Taunt; 2: Ray of Enfeeblement, Mirror Image, Improved Phantasmal Force, Web, Detect Psionics (DS), Glitterdust, Invisibility; 3: Blink, Dispel Magic, Haste, Hold Person, Protection from Normal Missiles, Slow; 4: Charm Monster, Emotion, Fumble, Illusionary Wall, Improved Invisibility, Mnemonic Enhancer (was Rary's Mnemonic Enhancer), Rainbow Pattern; 5: Chaos, Advanced Illusion, Bigby's Interposing Hand, Wall of Force, Teleport, Hold Monster, Dream; 6: Anti-Magic Shell, Enchant an Item, Eyebite, Geas, Legend Lore, Mislead, Veil; 7: Banishment, Prismatic Spray, Reverse Gravity, Shadow Walk, Teleport Without Error, Spell Turning, Forcecage; 8: Antipathy-Sympathy, Maze, Polymorph any Object, Prismatic Wall, Screen, Serten's Spell Immunity; 9: Astral Spell, Time Stop, Foresight, Imprisonment, Prismatic Sphere, Wish; 10: Prolific Forestation (x2), Prolific Vegetation, Rolling Road

Little is known about Trinius. It is known that he lived on the planet of Athas for the beginning of his mortal life. Then he began a rare transformation: that from mortal to that of an avangion, one of the good-aligned higher beings of Athas (described in Dragon Kings - ed). Of his transformation, again, little is known except that it took many long years to complete it. When it was complete, Trinius was no longer mortal. He was a fully transformed avangion, a glowing being of pure light and cerebral processes. His body had become more or less a flying wingspan, stretching ninety feet from tip to tip. When his transformation was complete, he foretold that if he were to remain on Athas, he would to die, undoubtedly killed by one of the dragon sorcerer-kings who feared a powerful force for good. Thus did he come to the Beastlands, where he settled in the shadowy twilight layer of Brux around an oasis of the sweetest water. Some would mistake his motives as cowardly, as Trinius no longer seems to care about his homeland. Instead, Trinius would argue that by remaining in the Planes he can continue to gain power until a time when he can return to Athas to destroy his one-time enemies. Or, Trinius might say that he doesn't care about Athas anymore, and has decided to let the dead world die.

Zealotry in the Streets of Sigil
The injust tremor at the mention of the name of Avangial, an aasimar of obvious asuras descent who has mastered the art of psionics and uses his powers in order to punish the guilty and bring goodness to the world by his own particular method. While claiming to act for the good of all, Avangial himself falls into a shadow of gray; his methods in destroying the unjust are questionable at best. He's been known to kill tieflings merely for their fiendish tails and known to kill those that break his strict moral code. He wanders the streets of Sigil, psionically probing the minds of the lower classes, attempting to find evil within them. When he does find evil, he strikes in the name of all that is lawful and good.

Avangial
Male aasimar (asuras) planar
3rd level Psionicist (Telepath), Sign of One
Neutral (Good)

Str: 13 Int: 14 hp: 17
Dex: 11 Wis: 19 AC: 7
Con: 16 Cha: 8 THAC0: 19

PSPs: 56
Psionic Powers:

Psychoportation:
Devotions: astral projection

Telepathy:
Sciences: mindlink, probe, tower of iron will
Devotions: contact, ego whip, empathy, ESP, invisibility, mind blank, truthear

Equipment: short sword, leather armor, small shield
Special Abilities: detect lie (3/day), half damage to cold and fire, 10% magic resistance, +4 to saves vs. charm and mental domination (+8 with wisdom adjustment)

Born to an asuras father and a human mother in Elysium, Avangial came to Sigil when he became of age and immediately saw the evil that his father had always talked about manifest in the city. Fiends were allowed to walk the streets with impunity, and their hideous children the tieflings were almost everywhere to be found. Avangial saw the chivs and cross-traders of Sigil attempting to make a profit off of almost everyone that they could. He saw a lack of morals, a lack of ethics. In short, he saw evil rampant in the streets of Sigil, and took it upon himself to become the savoir of the town. He walks the streets of the Hive Ward, the Lower Ward, and has been known to frequent the Lady's Ward. He is wanted for the murder of a priest of Tyr by the Harmonium, but has thus far managed to escape their patrols. When angry or excited, Avangial's eyes are known to flare brilliant gold. Cutters looking for his help in almost anything had best beware: he's extremely fanatic about his devotion to goodness, and may attempt to purify the sin right out of a group. Of course, in his eyes, most everything in Sigil is a crime: he's been known to kill the avaricious merely for asking for a little garnish. He treats tieflings and fiends as his mortal enemies, but is intelligent enough to stay away from full-blooded fiends, knowing himself not powerful enough to face them in combat yet. Tieflings usually aren't so lucky.

Actually, you could fold the anti-Doomguard and the anti-Dustmen sects into one group. While I don't have a good name for the sect itself (maybe something related to Elysium?), their nickname could be The Optimists. And it would have to be said with a sneer.

Yeah...you can ignore my Elysium comment. Hehe...

Hmm...how about Brightlanders, to reflect the pervasive illumination of Postive? I like the nickname of The Optimists though. I could totally see a scene playing out, a horde of demons charging towards a group of planar adventurers and an Optimist in the group saying, with perhaps just a bit too much brightness in his voice, "Don't worry guys! We'll get through this!"

I don't have any ideas for the rest of your sects though.