User blog comment:GeneStarwind/Monster Appreciation Day!/@comment-92.7.8.61-20110604085118/@comment-1696682-20110604130754

The way I see it, your using your whetstones (or fish) to smooth out imperfections on the impacting surface of the hammer, allowing more mass to contact at the exact time, thus "sharpening" the blow, allowing maximum damage. Same goes for Hunting Horns.

At least, that's the best I can come up with.