Gogsitis: Sorry for the guys who seem desperate but... this thread is actually all the tribute you need for the game. Just look at how many ways there are to kill him, and already showing the specialties some chose.
I completely disagree with this. There is one disproportionately good way to beat him, and that's with almost exclusive sword use. I am a magic build, and attempts to intelligently use all of my signs failed (I died about 25 times) because he usually did the same thing I was trying to do, but faster (even when my signs cast properly, but especially when I stood there for 6 seconds doing nothing while I tried to cast with full vigor) and better. Igni, traps, bombs (an entire inventory of them), and throwing daggers barely made a dent in him.
I came here, read that most people who were successful by being aggressive with the sword (possibly using daggers or Aard to allow continued sword use) and beat him on the very next try. So, sword is so much better (against this guy, but possibly in general) that even someone with 0 points in the sword tree is more successful with the sword than using any ability they've put points into.
It's additionally frustrating that in order to have potions in the battle, you need to load an older save and race through the cut scenes so that they don't expire. Or, as some suggested, load an older save and stock up on a particular type of bomb, or daggers. There's a big difference between a challenge and requiring your character to know what is about to happen to him in order to not die - it really pulls you out of the world if you need to die, go back, and prepare based on what you learned by dying by doing things your character would have no way of knowing they needed to do yet. Maybe this is fine for an Emerald Weapon (or for non-FF7-fans, a super-hard endgame sidequest that is only really for people with the game guide that have played the game through 4 times), but not for a main quest line.