Thanks for the answer and the welcome!
I guess a flat bonus would be completely overpowered, but I had to check since it makes a huge difference to the value of the feat at very low dodge/evasion skills.
Completely forgot about the combat stats page, so I was missing something obvious afterall, oops. Now I just need to decide whether or not it's worth it considering I plan to leave both skills at 0. Probably not, though I like having it from a flavour perspective.