Beowulf source for Alien blood

I know a lot is made of how Gieger's designs reflect art from Egypt, specifically Nut and Geb. I am wondering about other possible sources. I remember in Beowulf that Grendel's mother's blood melts the sword used to kill her, the exact line being "The sword shrank from the battle-shed blood;/it's blade began melting....The sword had melted./It's banded blade was burnt by the blood,/ so hot was the terror, so acid the evil." (1418-1429). A few lines later she is called an alien evil. I think the Alien is a mix of old horrors rather than a direct descended of one mythology. That leaves two choices. One is that the mix means something deeper, like a call to the darker parts of life, or the mix is just a bunch of cool, scary stuff the writers used both subconsciously and consciously.