Mihawk med-high dif, Ao Kiji was a good match up against Akainu and isn't on the same tier as Shanks, Mihawk, Akainu, Kaido, Garp etc.
Kuzan wins, after hearing Oda's words about Akainu and that fact that Akainu barley beat Kuzan despite having a DF advantage, I'd say Kuzan wins high-dif.
So. Mihawk clashed with Shanks numerous of times someone who blocked Akainu's magma fist easily with his sword I think that should give you an idea of who wins here U_U.