Chapter thirty-seven of Beowulf defines what the epic hero believes to be the characteristics of a good king. Beowulf tells Wiglaf, upon his death bed, what a good king will do (or does).
“There was...none at all, who would bring war-mates against me and threaten me with horrors. I observed social custom in my home, and cared for my own with justice. I did not seek feuds, nor have I falsely sworn any oath...[and] I did not kill my kinsmen!"
It is in this paragraph that Beowulf defines the very specific characteristics of a good king.
1) No other kings tried to bring war against Beowulf or his kingdom.
2) Beowulf, as a good king, was always true to the customs of the Danes.
3) Beowulf, as a good king, was just (correct and lawful) in his laws.
4) A good king makes no promises he cannot keep and does not seek out battles (feuds).
5) Beowulf, as a good king, never killed any of his own people or family.