Beowulf is characterized as a hero by the semantic field.
Explanation:
At the beginning of the excerpt, the object, Beowulf, is characterized as one that looks and is part of liege-kinsman, investing him in a very particular role, specially by mentioning Beowulf's father (Higelac). The adjectives and adverbs also contribute to this characterization ("stood up straight and stoutly did seize him".) The actions referred to the speaker are also impressive due to the sound of them (crackled and outward repeat strong consonant sounds such as "k" "r" or "t").
Those lines contribute to Beowulf's characterization as hero in three aspects. First, "[the] liege-kinsman worthy of Higelac (...)" makes reference to the fact that he is a person that deserves being admired and followed by the people. Second, "stand up straight" and "stoutly" refer to his physical appearance and his attitude while giving a speech regarding his coming battle against Grendel. Third, "[his] fingers crackled" and "[the] earl stepped farther" describe his courageous attitude as he does not hesitate for a moment before the fight. To conclude, he is characterized as a hero because he is claimed to be worthy of being followed, have exceptional physical traits and a warrior's fearless attitude.
