Mihawk was superior to Shanks at the point of their last fight. Both were world renowned and that got both to the positions they acquired. It was the latest update they had about their contest of strength, but after that, nothing. Not saying the dynamic changed but more than a decade past and both grew independently from the other.
I don't see nobody sayin fruitless teach is comparable to shanks and mihawk tho
Also if we count the fish attack as a genuine feat wouldn't that mean mihawk would have likley lost his arm too?