Haku

Grendel is easy to beat, once you know how... You need to use the Harpoon cannon whenever possible, and little fire arms and torpedos work too... But you MUST NOT ATTACK THE FEET! He will squish you if you do... Attack his head. Once he starts holding his head and thrashing around, keeping attacking him until you get to the part where Dratchma says you could push him into the canyon. Attack him with the Harpoon cannon and that should knock him into the canyon.

Hope that helps... ~.^