This is a
causal Mihawk sword's swing:
I am not talking about a technique, much less a strong or even the strongest move: it's just a nameless slash.
What if Morely somehow evaded the slash? By Holy City?
I am not saying he has it 100%, I am saying that he fighting Morley in a place in which he himself said "It's impossible to fight here" It is not proof in one sense or another.