User blog comment:Auraestus/Just to put this out there..../@comment-25356210-20151102134551/@comment-26116279-20151102152022

They were probably invented after the fall of the mountain as a counter to dragons. Durins bane is a maiar, completely different class of creature from balrogs (plus how would you use one of those inside). Also, dwarven axes were enough to nearly beat the father of dragons in battle so...