I'm afraid, though, that that's a misreading (or at least reinvention). The relevant passage starts at line 661.
Ða he him of dyde, isern-byrnan,
helm of hafelan, sealde his hyrsted sweord,
irena cyst ombiht-þegne,
ond gehealdan het hilde-geatwe.
Gesprac þa se goda gylp-worda sum,
Beowulf Geata, ær he on bed stige:
"No ic me an here-wæsmum hnagran talige
guþ-geweorca, þonne Grendel hine;
forþan ic hine sweorde swebban nelle,
aldre beneotan, þeah ic eal mæge."
Translated: "Then he took off the iron byrnie,
the helm from his head, gave his decorated sword,
the best of iron, to his attendant,
and ordered him to hold the war-equipment.
That good man spoke boastful words,
Beowulf the Geat, before he went to bed:
"I never supposed myself poorer in battle-strength,
in battle-deeds, than Grendel himself;
Therefore I will not with a sword put him to sleep,
deprive him of live, though I easily might."
So sure, Beowulf takes off his armor and hands over his weapons, but to imagine that he strips completely is pure fantasy.