An erection sustained by a corpse.

The etymology is obvious. Lust occuring at death: lusting after angels.

Causes

Angel lust is usually the result of a traumatic death, especially asphyxiation. High levels of arousal — not necessarily sexual — coupled with the final spasms of the nervous system result in some very unfortunate triggers being pulled. Ejaculation may even occur. The penis has its reasons of which the brain knows nothing.

All corpses undergo livor mortis, the posthumuous accumulation of blood pulled earthward by gravity. When corpses are positioned upright or face down, blood is drawn to the lower extremities and/or the front, resulting sometimes in angel lust.

Uses

A vanquished foe displaying angel lust makes an excellent war trophy. There is no better way to humiliate your enemy than to display their posthumous boner. Possession of a corpse with angel lust is an excellent way to earn the respect and kudos of your comrades.

Additionally, a penis with post-mortem tumescence carries all the horror necessary to cast a wicked spell. Ideally the dark aura can be directed toward crushing the sex organs of a nemesis. Attending hangings in the town square is an excellent way to procure this little token. Bring a knife.