You know how people in RPGs sometimes fight with their bare hands when unequipped without a weapon? Well, maybe we should EXPAND on this by having your character attack with their butt, belly, or their full body weight when they don’t have a weapon equipped (with higher weight meaning stronger attacks) as long as the immobility setting is disabled on the options menu. This would mean that you’d give the succubus boss a taste of her own flabby medicine. 
I was planning on adding a class called Fatzerker where you can sacrifice weight to increase the power of your skills. And of course the skills would be like body slam or heavy blow or some other play on weight. So kind of along the same lines as your suggestion except the skills actually have a weight cost to cast.
The interesting part is coming up with lore as to why that’s even allowed, but I’m sure I’ll think of something.
Well, I think that the skills I referred to apply to all classes, with the Fatzerker spending weight in order to use them.