Solace means comfort in disappointment or misery. Beowulf and his men travel to Hrothgar's kingdom to provide solace to king Hrothgar and his people the Danes Solace is in 2nd person.
Grendel is the fiend in the story of Beowulf because he comes from a deep dark cave that is depicted as hell. A Fiend is an evil supernatural being. The part of speech is second person.
Sinew is a band of tissue connecting a muscle to its bony attachment. When Beowulf severs Grendel's arm from his body the sinew keeping his arm attached to his body is detached from his shoulder. Sinew is in third person.