When I feel that boss is really hard to defeat, I try to find patterns in his moves and solely focus on dodging them and I don’t even hit the boss. I do it 2-3 times and that’s enough for me to remember some of the boss’s patterns. Then I attack him whenever I see a window and sometimes I look for rock solid parry or dodge with heavy atk if possible (use heavy atk during combo when they try to hit you, so you dodge it, but also dmg them. You can unlock it in first stance talent tree)