Dual wield is simple to introduce, instead of having a weapon in each slot, make it a pair, so gladiator can use a brass dagger, but not brass daggers, like how fist weapons work, one pair equipped in main hand slot. If you did have a dual wield class, ninja could easily come off it, just that the weapons they can equip would be ninja only, and you could make them, you know ninja style weapons, this is already in the game in a way. Look at the primal books, Scholar books can only be used by scholars, while the summoner book can be used while just a mere arcanist. Ninja I think it would be funny if they just gave a big "FU" to the XI crowd and made ninjas a ranged dd class, I think in earlier games their specialty was throwing weapons, they could always toss in ninjitsu to make up for it, but all utsusemi would end up being is a featherfoot with a mystical animation. Lancer could easily have a tank class, let's call it Tankinglancer(TLR). Tankinglancer's spears would be one handed, TLR only, and that would free up a spot for a nifty Spartan like shield, but out of respect for 300, their AF armor would need to have then men's ab show, not the ladies.