Seems like Zoro legit hurt Prometheus, not just a wind slice that split him in half. With begs the question, how the hell is this even possible?
Notice how Oda chose to place the panel, the first panel with Kaidou, a slash in the neck. And the 2 after him, it looks like Zoro is placing Kaidou's head on his sword, with him saying he needs more power from Enma
This was shown when Shanks stopped akianu's magma from reaching Coby with barrier haki.