Connection to Beowulf
"Wise sir, do not grieve. It is always better to avenge dear ones than to indulge in mourning." (l.1384-1385)
"Then the gold hilt was handed over to the old lord, a relic from long ago for the venerable ruler. That rare smithwork was passed on to the prince of the Danes when those devils perished; once death removed that murdering, guilt-steeped, God-cursed fiend, eliminating his unholy life and his mother's as well, it was willed to that king." (l. 1677-1684)
"The treasure had been won, bought and paid for by Beowulf's death." (l. 2843-2844)
Connection to Grendel
Wergild: Beowulf vs. Grendel
In Beowulf, the "cost" (though not monetary) of Grendel's death is a man close to King Hrothgar, whom Grendel's mother kidnaps and kills from the mead-hall. Similarly, in Grendel, there is never a mention of money as compensation for a man's death; when one man kills another in the meadhall, he men either "excuse him" or "send him out to the forest" to live in isolation. Grendel, as well, kills without thought of compensation. Therefore, Grendel does not deal so much with upholding the value of wergild, but rather with abandoning it.