Beat Darkbeast Paarl. There's an enemy in Nioh very similar to him. Anyways, I've come to find that just going ham on the bosses is the best way to beat them. First ry against Paarl I tried just doding his attacks and he killed me after I only got him down 1/4 health. Went back, got in his face and destroyed him, although the last 1/4 of his health I could barely hit him due to his stance. Might have been better to unlock from him and focus manually on his legs. Also, Henryk's gear made it a lot easier I'm sure. Barely, if at all, took damage from his eventually bolt attacks.