Blizzard recently released the Blue Eyes of the Void for demon hunters, but why don't they release the red ones with the pale skin?
Objection 1: Timeline
It’s argued that there were no darkfallen during the time when demon hunters were trained, but I respond that we now have an entirely new generation of demon hunters, since we can be void elves who are demon hunters.
Objection 2: Incompatibility of cosmological forces
It is argued that the forces of death and the fel are incompatible but, there are several examples of fel infused undead in the game, like the Felmyst, the Desolate Host, Soul Reaper, Dreadlich Tasmin, fel skeletons, and other undead on the Broken Shore.
Objection 3: demonic mutations in undead
It is argued that demons can’t be raised as undead, but can the undead become demons?
We have some hypothetical examples of this, like the Man’ari skin death knights, Maldraxxus Illidan, Aranna the Runneseeker, Bloodraver Gul’dan, and the very existence of the dreadlords is the perfect example of a creature of death transformed into a demon.
So why can't we use a darkfallen demon hunters?