“Eoton” is probably most easily and commonly translated as “giant,” on the basis, it would seem, that its etymological ancestor is the “Jotun” of Norse mythology, who were creatures of godlike strength who dwelt in dark places. Someone has suggested that the Proto-Germanic word for “jötunn” (Old Norse), which is “etunaz,” may have the same root as “etan,” or “to eat,” and accordingly had the original meaning of glutton or “man-eater.” Unfortunately, the source for this assertion is lost, so for now it goes unsupported. Further research will be needed.
Whatever the truth, I think “giant” is a poor translation. Giants in our contemporary English are part of a child’s imagination. If you read that, for the night, the king’s own soldiers offered “eotonward,” or protection against invading giants, you would laugh. The context in which the word “eoton” appears may indeed warrant comedy: the Great King Hrothgar, to some scholars’ readings, cowers in bed behind his men, while Beowulf antithetically lays down his sword so that Grendel and he can have a fair fight. Grave, though, is the threat of being eaten to the Beowulf-poet. The text invariably treats the concept seriously. “Eoton” may be better translated as “man-eater,” especially since in our minds a giant is false, but a cannibal very real.