i'm having trouble at first too. but those critical strike for 200+ damage
comes from his arrows i think. so i use the terrain(dragon bone) to block those arrows.
when he had shot his arrow, i rushed at him and start using my fav move in the game, the jump strike!!
and make sure u have a lot of potions. don't be stingy to use 'em. i used it quite a lot.
this game is quite hard at lower levels. but when your at level 25++, do the flying fortresses,
and u'll be fine.