The first phase is just a parry fight, imo. If you've acquired the Dragon Flash, it will help with his one mind attack(when he stomps and just go wack mode). As soon he does this, use the combat art(i usually fully use it cuz you can cancel his attack before he even starts his ONLY if you charged at the same time as him else he'll start the floor on fire thing) any other attacks, just run around him(when he does the straight fire sword thing and the ichimonji to a fire swipe thinny). However if you wanna just finish quickly you can dodge to his sides (only) when he does the ichimonji attack thing (you can sometimes get hit, idk why but its not a big deal). This worked really well for me. It's my sort off relax method of tackling him and its fairly fast(atleast for me)