It's the complete restriction on glaives that makes me think they are being saved for something. It's just way too iconic to Warcraft 3 to keep them restricted to NPCs.
I remember when we got this datamined in Cata's beta, and we all freaked out about how awesome this would be as a raid or heroic drop. Sure enough, this awesome custom model was wasted on nothing more than being a weapon for cultist NPCs in Blackrock.