Which they have - Osiris has Feed, so it slowly builds up its attack power as it is used successively. Arbiter busts through shields, and otherwise blasts enemies away when they get hit to create some breathing space. Each weapon also has uses outside of combat, like carving up vines or smashing brittle walls. How else is something supposed to "work differently" other than the actual functions a weapon is supposed to have; power, speed, reach, and additional effects? Seriously, in what way can a weapon "work differently" like you keep saying?
I didn't say that at all, that's just...why the Eryx are used differently. It's part of this Dante's "rough around the edges" style, same with how his Rebellion animations show a lot more force behind his swings, because he stumbles on the follow-through. This Dante just has a different kind of style that the classic did.