One can only defeat so many villains that want to "cover the world in darkness" before one starts to look for a different flavor of horrible.
EVIL JUST GOT EMO!
In the days of old, before the dominance of humanity, the giants were the supreme rulers of the world and their crafts were considered to be the best. These beings venerated the god of the forge above all others and their swords and armors were the best that could be had even in the days of their decline. A hero seeking a masterwork sword might have to voyage long and hard to find a surviving giant smith or cache of rare and valuable giantcraft weapons.