Hyperbole because your feet really can't fall from walking.
Answer:
No error is the answer.
Explanation:
The sentence is completely alright. There are no mistakes at all.
Beowulf is battling against evil because he sailed to the Danes to rescue them from Grendel. It is evident in lines 195 onwards to fight Grendel. SO when the night came, Beowulf and his warriors waited in the hall for Grendel to come. Together with his warriors, they sailed to help King Hrothgar defeat Grendel who continued to kill his men.
The recurring theme of "fate vs. man" shows how a weird and cosmic chain of events and temptation is unavoidably going to affect the protagonist.
Hope this helps!