Answer:
I think its because Beowulf sees Grendel's mother in a cave. He tries to hit her with his sword, Unferth's Hrunting, but it fails to pierce her skin. So he throws the sword away and attacks the mother with his bare hands. ... Meanwhile, the blade of Beowulf's new sword melts because the blood is too hot and poisonous for it.
Step-by-step explanation:
I learned about that alittle