Caduceus ex Mare Imbrium
Warp Staff: The engraved runes and icons of might wandering around the surface of the staff have grown to cover it, so every visible part contains images upon images within images; some appear as maddening fractals and others resemble ghostly, screaming faces. The iconography has so taken over the staff that it partially controls the motions of the wielder in erratic ways, making him miss the target when he otherwise would not, often with the afterimage of warpfire behind his motions.
The Caduceus was encountered by the XVI Legion during the First Pacification of Luna. It was wrested from a force of purebreed moon warlocks who had benefited from Cardinal Tang’s genetic empire. At the time, it was thought by the XVIth Legion’s leaders that it had been forged there, in the depths of the Mare Imbrium, but all records of the staff in that battle have long been lost. After the pacification, the XVIth Legion remanded the staff into the hands of the Adeptus Terra for safekeeping.
The Imbrium staff wasn’t seen again until hundreds of years later, during the Horus Heresy. It was wielded by the XVth Legion against Loyalist forces. The Caduceus ex Mare Imbrium may have been a gift from the XVIth to the XVth, or the latter may have taken it during one of their infamous raids to obtain profane knowledge and forbidden artifacts.