I think Law's Devil Fruit can actually bypass Armament Haki because Law doesn't really damage you so he doesn't need to cut through armament haki, he just seperates your body parts when he hits you inside the room.
I'm 100% sure that Vergo was the better armament haki user than Law, even Doflamingo was sure that Vergo has the better haki mastery out of the two, but Law still cut through him without any trouble, there wasn't even a clash or anything.
I'm 100% sure that Vergo was the better armament haki user than Law, even Doflamingo was sure that Vergo has the better haki mastery out of the two, but Law still cut through him without any trouble, there wasn't even a clash or anything.