I'm doing both the corruption and clean routes and with Valravn, because I did all of the training sessions and went for the skill option against Michael and the horn, I ended up having for the clean route 81 power and 22 skill, and for the corruption route I ended up with 84 power and 22 skill.
Now, I actually fought Valravn before having those stats, and that is because I fucked up and lost the clean route. Still, I won against Valravn with 78 or 79 power and lower skill in the corruption route, but I won with Brianna's help. Nico treated me like shit, now because I lost the clean route I re-did the whole VN, this time doing everything right (Skill against Michael, the horn, and all of the training sessions). This time, I won against Valravn with no problem, Brianna didn't have to help me and Nico actually congratulate me.
Because of that, I re-did the corruption route too, with all of the same shit and killing everyone to get all of the corruption I could (Which is 25, I don't know if you can get more, but that's the highest I got), I did all of that because the corruption route, just like you saw, gives you way more power, even if with this update, both routes end up with almost the same amount, and yeah, just like I thought, I also won with no problem.
So, my point is that you can either win with Brianna's help because you didn't have enough power and skill, or win with no problem because you had enough power and skill, in the case of both routes.