The literary device used in these lines is Personification.
The personification is a figure of speech in which a thing is given human attributes. The non-human objects are portrayed in such a way that we feel they have the capacity to act like human beings. This device makes the piece more interesting to read and makes it more sensitive to the reader.
I don't get it either maybe try google just trying to help
Shield Sheafson- The legendary Danish king from whom Hrothgar is descended, Shield Sheafson is the mythical founder who inaugurates a long line of Danish rulers and embodies the Danish tribe's highest values of heroism and leadership.
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