Remathilis
Legend
Like everything else with Psionics, it widely varied. The 2e psionicist had to pick a primary discipline (one of the five options) and then picked sciences (major powers) and devotions (minor). They could pick other disciplines as they leveled, but never more than half their powers could be from other disciplines. In 3.5, you picked a discipline, but it just gave you a list of bonus powers you could learn in addition to the generic psionic list. Very similar to how the original 5e warlock worked. I think 3.0 was similar, but I think you had to pick so many from your primary discipline like in 2e. And I don't know how 4e worked (was long gone when it came out) but I think there was no limitations on the powers you chose.i can't say i really know the workings of psions in previous editions but i thought they at least actually had to stick to one or two specializations/domains/power spheres? or end up a jack of all trades, a psion might spec into telepathy and pyromancy and have potent telepath and fire abilities beyond what an equivalent caster of their level might have but wouldn't have the diversity of spells they'd have.
So a 2e psionicist focused on one thing and picked up a smattering of everything else and a 3e could pretty much pick whatever, but got special access to unique powers based on their discipline. I would put it on par with a wizard focusing on a specific school or a cleric with a domain.

