I think it would be nice if we had these classes. Perhaps under the current job system we have you could start off as a Ronin or Thief and then when you hit 30 you have said classes available to obtain via questing. (Ronin = Samurai, Thief=Ninja) The samurai would be A tanking class that uses Katana's and would maybe specialize in aoe taunts or other ways of gaining enmity and the Ninja would be a DD class able to dual wield kunai like weapons like in FFXI.