Леля
Auto-translated
It's all about conventions, or maybe the sword is like an extension of the vampire, implying they're connected on some level (perhaps mentally), and that's why it drains life. Basically, you can weave any story you want, but a vampire with a sword looks cool and is simply aesthetically pleasing, unlike one with claws.
Added 4 minutes later
It's strange that this is coming from someone who plays Haven!
