Turned in may stacks of Vampyre Fangs and got faction per quest and 300 bottle of holy water.
Place in necro range slot and emptied 100 of the bottles into a light blue named vampyre in the TM. Did not note any hits or damage from any of the 100 bottles my 70 level necro threw at the guy. So not sure if it does anything but give you faction. Faction hits are not that great as I turned in about 6 - 8 stacks of 20 vampyre fangs and did not seem to give much faction or exp.