I'm so sorry I completely forgot about this.
Try using a melee build. Black katana from the smuggler at the docks at night. Shirt of rage and cloak of speed.
I don't remember the exact build I had forgotten this but these were the core items which boosted my attack and evasion.
I also had the Uberlab mode from training with the hermit, Ring of luck and bunch of greater healing potions from the infinite money trick.
Edit: these were my stats at the end of the game from my current safe file.