Hussar
Legend
/snip
And, no 'mystic' isn't a great name - not if you're going to keep calling the powers 'psionic,' anyway.
Well, we still call them clerics and bards and wizards, despite them both being spell casters and casting spells. Saying that a mystic uses psionic powers isn't that different is it?
To me, I'd look at something like the Jedi. Which would describe Jedi better? Would you call Yoda or Ben Kenobi a psion or a mystic? Again, for me, mystic fits the bill much better, since psion or psionicist is a purely D&D thing that is only self-referential. Mystic implies an otherworldly cabalist that deals in the mysteries of the universe. IOW, an interesting connotation that carries all sorts of RP goodness. To me, a psion or psionicist is a flat, D&D only term that has no actual connotations and evokes very little.
Again, just to be 100% clear, I'm only talking about myself. The only archetype references I've seen in this thread for psion come from D&D novels, which, honestly, I don't read. So, obviously, the word carries little weight for me. Mystics, on the other hand, have thousands of years of real world traditions to mine for inspiration.