Answer:
it will bring the hero greater honor to slay the foe with his bare hands.
Step-by-step explanation:
this is partly because it would be dishonorable to kill an unarmed man, no matter how dangerous or evil he might be, and partly because Beowulf's vanity will not allow him to miss an opportunity for even greater glory, even if it means his death and disaster for the innocent people he professes to defend.