Uhm, how much sense does it make for a thief to tank? a thief isn't supposed to get *caught*
a thief wont use heavy armor, or def skills, so they will get 1-shot=bad tank, unless they get 100% dodge chance, which wont happen (maybe 1-3 hits, like mana wall, or such, but that wouldn't be enough, for same reason BLM don't make good tanks)
and how much sense does it make for THF, to aggro? more likely they would get aggro-reduction skills.