Psychic warriors are base T3, though they're the strongest in the tier, on average. They're consummate gishes and can keep up with most wizards in actual games, remaining viable all the way to epic (assuming you know how to work around their weaknesses, which is the trick).
When you start adding in the various psion powers they're able to grab (which includes wizard spells through spell-to-power erudite), mantled warrior, soulbound weapon, and their ability to manifest 9th level equivalent powers via augmentation, you can bump them up to T2 with reasonable efficiency. This is doubly true when you have access to power point recharge.
Linked Power, Schism, and psicrystal buffage all help them overcome the action efficiency disadvantage inherent to gishes as well.