Final answer:
The reference to "Almighty's enemy" in line 59 is a kenning for Grendel, the monstrous antagonist in the Old English epic poem Beowulf.
Step-by-step explanation:
In line 59, the reference to "Almighty's enemy" is a kenning naming Grendel. In Old English literature, kennings are figurative expressions that replace a name or a noun, often in poetic contexts like Beowulf, from which this line is drawn. The phrase "Almighty's enemy" refers to a being that is in opposition to God, and in the context of Beowulf, this describes Grendel, the monster descended from Cain who terrorizes Heorot, the mead hall of King Hrothgar.