I have a crazy head cannon thats been on my mind for quite some time now. Think about this. How much do you think grendels arm weighs? The arm is thick and meaty and is probably taller than beowulf. How does Beowulf have the strength to hold it? It's gotta weigh at least 300 or 400 pounds. Second, do you know how huge Grendels mother is? How could Beo defeat her on his own? Simple, i think beowulf is a gigan-human hybrid who is unlocking his gigan potential. Remember how Scythana transformed into a gigan monster the more she fought? Maybe the same can apply to Beowulf. Like I said, he's unlocking his potential but hes doing it slowly.