Shanks has never been confirmed to be a swordsman so the argument is daft
- We don’t actually know how xebec is doing what he’s doing with his swordsmanship. We do know it looks different from divine departure but that isn’t the point
- Nothing in the story even halfway implies mihawk having even comparable haki to shanks let alone better
Haki is used for everything
No same way big mom is a physical monster, has internal armament, conquerors infusion, and sword attacks doesn’t make her a good swordsman as we’ve seen. Her not even being considered a swordsman