In Beowulf, the sword Unferth lends Beowulf is named Hrunting.
Unferth gives Hrunting to Beowulf before the hero descends into the mere to fight Grendel’s mother. The poem emphasizes that Hrunting is an old, famous weapon with a reputation for victory. Its edge, however, fails to pierce the monster’s hide during the underwater struggle.
Beowulf ultimately finds and uses a giant-forged sword in the lair. That weapon succeeds against Grendel’s mother but melts after cutting through her and Grendel’s body. Hrunting is therefore important as a named weapon, but it is not the sword that wins the fight.
Readers sometimes confuse Hrunting with Nægling, the sword Beowulf uses much later against the dragon. They are separate weapons in the poem.