Not sure if it was mentioned for the whole frightened thing, but Barbarian Berserkers can frighten as an action at level 10, it seems to be non-magical the way it's written.
I wonder if it only being "frightened" in the mechanical sense and and not requiring an emotional reaction helps for those who don't want PCs to experience such things? (It could be reskinned as something more palatable in terms of explaining the reaction).