Why does this vampire with a knife bother you so much???? What would be better??? S. Stone with an ice axe??? And it's much closer to reality + it doesn't offend the memory of fans of Might and Magic 1-5!... And considering her freckled chest, it's quite possible to consider her undead....
IMHO, a sword for a vampire is a matter of taste... for example, if a player fights every day... and not just once... won't the vampire get tired of drinking blood from anyone he comes across???? He might even wear down his fangs....
Let him wave a sword in battle, and have dinner when his opponents take their turn......