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

It is not about Haki vs Haki. It is about DF vs Haki. Think about this: --(1) Rayleigh said that Haki passes through the DF defences and helps the Haki user touche the DF user's real body. --(2) In the first encounter between Luffy & Ceasar, Robin said that Haki does NOT prevent the DF user from using his DF. Thus, it is not like the seastone. --(3) In the Law vs Smoker, Smoker said that Tshigi's Haki was not strong enough to block Law's DF.

If you consider these it becomes clear. Haki does NOT nullify DF. It helps the user bypass the DF defence and can also block DF attacks. But if the DF attack is strong enough then BH cannot block it (like with Tashigi). Vergo did NOT try to block Law's DF attack. He just covered his whole body with BH. Also law put ALL his strength in this slice since he sliced all the laboratory and mountain. In other words, in just one moment Law's DF attack was stronger than Vergo's BH.

If it was Rayleigh he would have blocked it!!!!!