There are two characters with sword skills:
One of them (Mihawk) can slice a mountain into several pieces with extreme precision.
The other (Xebec) doesn't have that incredible sword-cutting skill because he lacks the necessary refinement and technique; however, he can create a powerful, blunt attack that can pulverize that mountain.
Which one has better sword skills, according to Oda's criteria? Mihawk. That's why Mihawk's sword skills are better than Shanks, Xebec, or Roger, and I've never argued against that.
However, Mihawk is weaker than all of them when it comes to power