If I recall correctly, there are 3 main attacks. A fire blast thingy, a horizontal arm swing and a vertical arm slam thingy. The entire trick to this fight is getting the right position to stand where he only does the vertical arm slam which you side step to avoid and then *Quoting Tidus* shoot like crazy!
I remember my new game++ tank build. I had fully upgraded Great shield of Artorias, fully upgraded Paladin armor set, a focus on health and resistance level and his fire blast would one shot me even if I had my shield up facing him!
Once I found the right standing position I thought I could kill him with lvl one naked character. --- (\ (O_O) /) Praise the sun!
If you can make it to the pathway...where you can hide...peek out towards the main path and you can take down the boss using bow and arrows. Will take a few arrows but it is without risk...as long as you don't "peek" out to far.