Question

Which character is described in these lines?

"Fearful in spirit, faint–mooded waxed he,
Not off could betake him; death he was pondering"

Answer 1

the answer is beowulf

Answer 2

These lines refer to Beowulf, and those are the actual thoughts Grendel had when he fought with Beowulf. He was surprised at his strength, but also scared, and wanted to flee, but, of course, that was impossible.