The Question and Answer section for Beowulf is a great resource to ask questions, find answers, and discuss the novel.
I'm sorry, my copy of the book is not divided up into sections. What version of the text are you using in class?
Finn called a truce with the Danes because he was married to a Danish princess. Her son and brother were both killed in the war between the tribes. Finn also lost many of his best men, which forced him to negotiate with Hengest.
Those kennings would be the "shepherd of evil" and the "guardian of crime".