Originally Posted by
Khrux
There is definitely no consistency across classes, some just buy the item for 8k gold, some get it from a tier2 class hall choice, others require multiple dungeon drops and a rep requirement, some are straight raid drops and 3(i think) come from withered training(Blood/WW/ProtPala) and then you have Prot Warrior that just loots an item from the open world on an unknown respawn timer.
So I wouldn't rule anything out considering the randomness of what each class/spec has to do for theirs. I imagine the undiscovered ones are the more elaborate, hence not being found after months of alpha/beta, such as Unholy and Frost.
I'm leaning towards our hidden artifacts potentially being in 7.1 as both Karazan and the Stormheim raid will have undead/ghost type mobs/zones/bosses.