My Vampire is Ezra, and she bites whether she is armed with one or two weapons (as long as "Vampire Bite" is on) and she will throw an axe if out of range for a bite or a weapon. It is funny how some ghost do give life bites and some don't.
For example, the ghost guards in Skull Castle who kept telling me I could pass for awhile, ended up being supper in the end and providing full life back to Ezra.
Mammawlin