What literary device is most strongly represented in the following line from Beowulf Follower and strongest of Geats?

The literary device most strongly represented in the line "Follower and strongest of Geats" is epithet.

An epithet is a descriptive adjective or phrase used to characterize someone or something. Here, "Follower" and "strongest" are epithets describing the hero Beowulf, highlighting his loyalty and physical prowess.