So if you believe that he is a swordsman its defacto that it doesnt matter how strong of a haki user he is he is below the WSS. Dont be one the guys who genuinely believe that "Shanks turned off his haki against Mihawk". In my book they are pretty much equal, and maybe Mihawk has the advantage after Shanks lost his hand, but my whole point is that he is a swordsman so EoS Zoro > both of them.
The WSS pretty much implies that whoever fights with a sword cannot beat Zoro. Its not a coincidence that both WB & Kaido were never seen fighting with swords even in their fb.