you have to get in between the both of them and then use ceberus spinning attack on the fire boss. The move defends you from the other guy ( I forgot if you have to be in swordmaster style for this). leave the fire boss with a little life and then concentrate on the other one with the rebellion cuz if you kill one the other one goes crazyyyy. So its best that you shorten the time you need to beat the remaining one. Beat on them like hell when you try to run to the side to jump on you. in my opinion the hardest boss in the game. stock up on life if you have to and good luck
u just hav to learn the patterns of attacks from the bosses, then with a bit of luck and skill, you should be able to pull through
