Silver armor, shield, and sword, use the ring that halves your damage. Start off by running around the perimeter of the platform, and go the opposite way Dark Fact is going. Once you hit him, try to get under him and go the same way he's going. You'll end up hitting him multiple times, as you run the same way, taking out the floor as you go along. This is the only way I could manage to beat him w/o getting trapped in a corner or something. If you run around and try to hit him once, you won't be able to kill him because you can't score enough hits without running out of space. I tried dozens of times to just run around the edge and try to make my way into the center, but it doesn't work. The only way you are able to hit him enough is to run with him in the same pattern and do your best to avoid the fireballs. Even with this strategy, it's all about luck.