This is the Spectral Cavalry Sergeant for the Necropolis faction in Warlord. Kevin Williams did a great job with this piece; I think it's great he used a Crusader helm (the goody-two-shoes from the game world for those not in the know) as the headpiece.

The spectral look is the same as on the Night Specter; Midnight Blue base layered up with Ghost White to Pure White. I'll probably go back sometime and do a greenish version of him (a la the ghosts in Return of the King).