It would be cool if Dante used that shapeshifting Rebellion as a whip-like weapon instead of just a grappling hook, as a ranged melee weapon of sorts, like Ivy's snake sword from Soul Calibur. I like chain weapons, like a kusarigama, but that wouldn't fit Dante much as it is a ninja's weapon and Dante is no ninja. Since it is Ninja Theory making the new game I wouldn't mind if Dante got a bo-staff like Monkey's from Enslaved, but with better and cooler moves.
Dante always gets guns for ranged weapons, but what about a demonic bow which he can charge up or snipe enemies with? Maybe that would fit Kat better if she should wield a weapon. I liked Lucifer in DMC4 (as the only weapon in that game Iiked) so I wouldn't mind seeing that returning.