in beowulf, how does grendel die?

In Beowulf , Grendel dies after Beowulf engages him in a fierce hand-to-hand battle in the mead hall of Heorot. Beowulf, choosing to fight without armor or weapons to match Grendel's own lack of them, seizes Grendel's arm with immense strength and tears it off at the shoulder. Mortally wounded, Grendel flees back to his swampy lair where he dies from the injury. Beowulf later displays Grendel's severed arm as a trophy in Heorot, symbolizing his victory