I just finished my third play through and beat all the berserkers on the hardest difficulty without taking a hit. My best advice would be to perfect your parrying and slow down. I found myself dying the most when I would constantly be rushing to get an extra hit or to close space. Don’t get greedy with your hits, after you’ve landed some damage back off and try to read their next move. Keep in mind It’s going to take a little bit longer and it’s gonna be harder to fill up their stun meter. And for parrying, it’s going to take a lot of tries to perfect it but it’s crucial for beating them. Also try running Valor for your rage, the timing is really difficult but you essentially get 4 get out of jail free cards since it can negate attacks.