These lines from the poem "Beowulf" refer to a sword that the Geat warrior finds among the treasures in Grendel's mother's lair. The sword is described as an ancient, giant-made weapon with an extraordinarily sharp edge. It is a prized heirloom and an unmatched weapon, except in the hands of an exceptional warrior like Beowulf.
His ancestral sword.
Beowulf uses a giant's sword to kill Grendel's mother in their underwater lair. He finds the sword hanging on the wall and uses it to strike a fatal blow.
He used his bare hands to rip the arm from Grendel as he did not think it to be a honorable fight to use a sword with Grendel fighting unarmed (insert pun here) He took Hrunting with him to take on Grendel's mother but it was lost in the fight, during the battle He found the Sword of the Jountons (giants) and slew her by taking her head in one mighty swing.