GOD DAMN! I just fought and defeated a lvl 48 Archgriffin I found, I'm only lvl 37. Boy, was that an intense fight. I died many times as it was basically a one hit kill type deal, however I was finally able to carefully line up my attacks and dodge swiftly, relying heavily on Quen for its cheap ass counter attacks. Of course, the treasure it was guarding was utter crap but at least the fight was fun.
I did the exact same thing with a Forktail that was level 15, while I was 7. Very intense fight, loved every second of it.