How do you beat the black knight the second time on Sonic and the Black Knight

When he throws his red balls hack away at em and your soul gauge goes up. It'll take once or twice but then when you get close to king arthur jump press b and slash. You'll automatically face in close combat with him. then you must do it again but its harder. in close combat the second time after his second slash he'll do faster slash so he does this(s=slow f=fast) ssfsfsf. It could take a while because it took me literally a day and a half to complete it.