Yeah assassin would be cool to have.

I'm thinking of these abilities: (strike abilities automatically added to your normal attack )

Death strike
Poison strike
confuse strike
Stone strike
Full break
Quick hit
Assassinate (auto death strike to ANYTHING that you attack from behind)
All or Nothing (converts Def stat to STR and can surpass your str beyond 255).

Ribbon
Back guard (prevents ambush)


Don't know why an assassin would possess ultima?