what are unique domain of arcane/divine/psionic

[With a box]

What domains are exclusive to psionics?
Or what areas are only can be done by divine casters?
(Let's not think about wish/miracle/reality revision)

[Helluin]

Psionics:
Time Regression
Fusion (If there is anything in arcane/divine magic that can accomplish anything like that, I'm not aware of them)

Strangely, there is very little that I can think of on the magical side even before you take StP Erudite into account. It seems that most things that can be done via arcane magic can be achieved/mimicked by divine magic and vice versa, because y'know, Archivists and Wyrm Wizards and Recasters and stuff.

[Bad Wolf]

Psions, Telepaths specifically, get all the crazy mind switching shenanigans.

[Prime32]

What domains are exclusive to psionics?
Or what areas are only can be done by divine casters?
(Let's not think about wish/miracle/reality revision)Psionic characters have direct control over their powers; they don't hand them off to outside forces like spellcasters do. This means there aren't a lot of powers with long-lasting effects outside of the user's own body (excepting Permanent and Concentration). Powers that can make decisions and act independently (like magic mouth speaking a message when it detects a certain creature) are almost unheard of.
It also means that psions have a lot more flexibility with each power, since they have no spell formula they need to stick to. A psion can easily adjust the strength of his powers by spending more or less energy, or change their damage type by altering its frequency. Rather than needing four different detect alignment spells, he can just look at peoples' auras directly and figure it out from their colour.

[Psyren]

Clairsentience works by reading reality/the Astral Plane directly, rather than asking for details from some outsider who might have their own agenda. Even arcane magic has to go to a deity or extraplanar being most of the time, e.g. Contact Other Plane.

Clairsentience is also more powerful than Divination, as a Seer can defeat mind blank and even Wish pre-epic.

[Segev]

Divine casting tends to get more and better access to healing/recovery effects.

Arcane casting tends to have better direct damage and non-buff utility. It has a couple of very specific buff effects which are superior to divine magic, but in general does less buffing and certainly less debuffing as an overall theme.

Psionics tends to do fewer permanent/long-duration effects, tends to favor flexibility within specific effects (kineticist powers, astral construct, etc.), and has astral/ectoplasmic themes. It also gets better mind-influence stuff at lower levels, particularly communication and suggestion.

[Zaq]

Outside of Wish and its cousins (which the OP says to disregard), only divine magic can bring folks back from the dead with more than a couple rounds elapsed from death to resurrection. (Psionic Revivify prevents divine magic from being a total lock on bringing folks back to life, but it won't help you if they've been dead for more than a few rounds.)

Only divine magic can make holy water or unholy water. (Well, holy water, at least. Arcane magic can sorta-kinda make unholy water with Blackwater Taint, but that's different from true unholy water.)

[DrMartin]

psionics don't have access to any illusion I think

[THEChanger]

psionics don't have access to any illusion I think

Psionics have some limited access to illusory effects, though they operate in a different manner than magical ones. Standard magic illusions create a non-real or semi-real object in space, which can be interacted with by anyone. Psionic "illusions" are found within the Telepathy Discipline, and interfere with the targets sensory input. They don't create anything, but change the information the target's brain is receiving. This limits their usefulness, as if someone comes along that the Psion was not able to target, they'll be aware that something is wrong.

However, it is interesting to note that False Sensory Input specifically works despite True Seeing effects as a Level 3 Power, and the other illusory effect the Telepath Discipline possesses, Microcosm, completely locks the target in a world of their own devising, an effect that I've not seen magic able to duplicate. Think Girard's runes that caught the OotS.

[DrMartin]

yeah but those effects of "sensory misdirection" are more on the line of enchantment powers than illusion ones. Even "psionic invisibility" (cloud mind) works on one subject at a time by erasing your presence from the target mind, rather than bending lights to become, well, invisible. So while you can reach a few of the effects usually associated with them, "true illusions" (eheh) are not something that psionics can do, as far as i can tell.

[The Viscount]

Psionics is the only thing that I've seen that can make the dream of metal, which is unique and complicated.

Arcane magic is the only one to get Ice Assassin, which is its own whole mess.

[Chronos]

Phantasms work by messing with your target's mind, too, and they're still considered illusions.

[Ruethgar]

Southern Magician Spellhoarding dragons with Magic Mantles and StP Erudite levels can switch about the abilities "unique" to a type, so I'm not sure that any of them can do something the others cannot except perhaps acess certain PrC abilities.

Only prepared casters that share some spells with the cleric can grant spells via Imbue with Spell Ability.