You are "The White Belt".

You possess an instinctual knowledge (along with muscle memory) of all martial arts systems ever created. If any new martial arts are invented in the modern era you will immediately gain instinctual knowledge of those as well...

...but only at novice level. You're also not able to improve your skill in any of these martial arts in the traditional manner, no matter how much you try to practice.

However, in moments of extreme duress...you will sometimes manifest a powerful golden aura: your eyes will turn blue and your hair will turn blonde-ish and stand up straight in an anime-like fashion. This is "Yellow Belt Mode", and your skill in all martial arts will immediately improve slightly.