If I weren't what I am, I probably wouldn't be able to sense it at all. That kind of power is dangerous to vampires; it's the same sort of power wielded by exorcists, onmyouji, and demon hunters. [He lets the fireball go away, and gestures at the sword he's holding.] This also helps. It's a holy weapon, and it's all but singing at you. It's only done that for me a couple times, usually when I was fighting something really big and really ugly.

[He puts the blade away now, and folds his arms.] Lovecraft wrote about things he called elder gods and eldritch horrors. Abominations that exist in dimensions beyond our own, the mere sight of which is capable of destroying a person's mind.