The Vestment of Vileness are a vampiric artifact.
This unholy article of clothing is a priestly vestment with a Sabbat blessing and curse upon it. The curse dooms the owner to lose any loved one who touches the robe. The blessing allows the vampire to use Necromancy (as the Giovanni Discipline) up to level four. The necromantic powers of the robe are not compatible with any Necromancy the vampire may already have.
References
Players Guide to the Sabbat, p. 153-154