What revelation about men does buck HAVE after attacking the Yeehats?

Buck realizes how easy they were to kill, and that he had no reason to fear them.

They had died so easily. It was harder to kill a husky dog than them. They were no match at all, were it not for their arrows and spears and clubs. Thenceforward he would be unafraid of them except when they bore in their hands their arrows, spears and clubs.