After Beowulf saves the mead hall from the threat of Grendel and his swamp hag mother, King Hrothgar rewards Beowulf with gold and horses - a customary payment for his deeds.
Morality is made concrete in the poem, with Beowulf as the "good", and the monsters as evil threats to mankind who must be defeated.
Beowulf was able to trick Grendel by pretending he was asleep. When Grendel slips on a puddle of blood, Beowulf is able to seize Grendel's wrist and rip off his arm.