Grendel's power does not compare to Beowulf's abilities because his power was used for a destructive purpose while Beowulf's power was used to redeem the victimized people. Moreso, Beowulf defeated Grendel so he is more powerful than him.
Explanation:
In the poem Beowulf, we learn of a vindictive monster named Grendel who used his powers to terrorize the people of the Dane Kingdom. Then came Beowulf a Scylding who left his kingdom to redeem the Dane's people from the monster. He wrestled him fiercely, giving him some wounds and eventually killing him. When his mother tried to avenge his death, Beowulf still destroyed her.
So, Beowulf was a lot more powerful than Grendel and he did not abuse his powers which was unlike Grendel.
I have acctualy seen hell... your right, its awful. even just thinking about it makes me cry. not to mention the screams! it sounds like thousands of people are being murdered...(prob true) no more details it gets really gory...DX