I have yet to confirm if this is indeed a bug or intended behavior, although I can't imagine how this could be deliberate:

I summoned greater molochs in the barbarian's glade by wishing for emperor moloch.
Then I froze the river and proceeded to throw the rune-covered trident at them.
At one point, the trident did not return and one of the greater molochs picked it up.
I started bolting them with magic missiles and some of them panicked, including the one that picked up my trident.
He then subsequently left the location and I permanently lost the weapon.
That's quite annoying since I specifically took raven starsign to get the artifact earlier and use it throughout the game.
Then this happens.