By trying to hit enemies, much and repeatedly.
The way I would go about it is to kill everything cornered (exhausted, trapped, etc.) by attacking them with the blunt of a sword, aimed at the head (the aiming is both for hide preservation and for additional training). Using the blunt is, again, both to preserve the hide and to get as much training out of it as possible. Note, though, that it's VERY slow.
I believe it's also possible to train a weapon skill by throwing the weapon (again, MANY times).