User blog comment:AYET/About the Busoshoku Haki armor/@comment-5536072-20121201154611/@comment-5536072-20121202002615

What cut the mountain was not Haki but the DF ability. And that is what cut Vergo as well. Otherwise there would be some blood there. And Law is not that great of a swordsman either.

I don't really know who lacks in math but I DO know what I read in the manga. And all the above that support my words are from the manga. But there is no confirmation about the "Haki vs Haki" theory in the case "Law vs Vergo".