it seems in the past Law's ability wasn't strong enough yet to cut Vergo but Law grew stronger, maybe if Vergo's Haki improved as much as Law's DF usage he could defend himself with his Haki
That makes a lot more sense, thanks.vYou don't know that. Law's Haki could be stronger than Vergo's or it could simply be Law's strenght with his DF has increased at a level beyond what Vergo's Haki can offer protection from.