I am adding vampires to my high fantasy world. These are not twilight vampires, they are more like the vampires from underworld or vampire the masquerade. I need to make them better fighters against soldiers in full plate, and traditional vampire features are not good for this.
But my vampires are not exactly traditional, so I could add a feature. The vampires in my world also have healing factors and enhanced sense but their healing uses up blood they've consumed and eventually they will need to drink more blood to heal. They are not harmed by sunlight, or garlic, or any religious power. Stakes to the heart will kill them as well as decapitation and going too long without healing from mortal wounds.
To make them better in combat, I wanted to give them bone claws like wolverine. I know many characters share superpower abilities, such as flight, invulnerability, super speed and so on. But it seems possible I could get into copyright trouble if I had a character exactly like Wolverine, or Spiderman or something, and only changed the name.
So my question is, is there a line to not cross? Can I get into copyright trouble by copying the idea of Wolverine's bone claws? If I need to worry about copyright, I'd welcome alternative ideas to improve combat readiness and stay in the general realm of vampires.