Vampire: The Trio
Makes you deadly
It makes bashing damage (ie punching) lethal, and
It makes lethal damage dealt by the wearer (ie stabbing) aggravated.
It only works if the wearer soaks the ring in their own blood, though they only need to do it once.
It is a brass ring with a large red stone, it looks like a class ring but it has no inscription or detail on the band.
Likely made by the Necromancer, given to Marsyas, who in turn traded it to the vampire-hunter Layla in exchange for a favor.