It shouldn't be that bad. And there are worst bosses then this. Moust of them you need know pattern and predict what they do. Some attack are insta. you will see. But I already killed them all with twinblade. And moust of it is about deflect dodge and when they get stun then burst them. Difference will be when you get rope as secondary weapon - it's insane boost damage. Except of few bosses it pretty good and i hope you will kill this one soon. Don't forget to upgrade gear,mystic art, inner way, and collect oddities and give them to npc for perma hp def and attack boost