Help with the final boss 51-wow (!!!) level (Vampyr)

I heard that the game will adapt to your ability - if you play poorly, it will give enemies weaker, if it is good, it is better - but I never thought that this will include the final boss so much. I have a 43 level, the final boss 51 is greater than the maximum possible in the game. Her health is drained awfully slow, although I use a Hatchet and Axe Glue booth, which demolished a lot of health. People kind, help Council how drain of the boss, what kind of imbalance?
Spoiler