Alright, so I finally came up with a mantle name that I was happy with:
Nosthermantle
nos (from nosferatu) + therm (i.e. heat) + mantle (already explained); when spoken aloud it sounds an awful lot like nosferatu
One problem though: Nosthermantle is 13 letters... Fake edit: Actually, what about Nosthrmantl? Again, I kind of like how it looks with vowels removed. It gives it sort of a Germanic feel, which fits with Nosferatu being a Germanic vampire. That's just me though, what do you guys think?
I would suggest Nothermantl instead. The missing e in the middle looks sloppy to me, but replacing the s with a th sounds and looks good.