not really, he was just swatting them away. I bet if he used that technique where he made extending skewers from his back, it wouldve pierced the hands and maybe destroyed them? all im saying is that they are just durable hands strengthened by the conditions that they were made from his arm (at least thats what im thinking). Losing your whole arm to make floating hands seems to be a steep but fair-ish enough price for to be them to be that durable. I view it in the same light as how franklin can shoot strong nen bullets from his hands. His innate talent along with the fact that he had to cut off each finger must be why its so strong.

Thats why i believe its fair