After MRF went insane/senile/bonkers at the end of the novel, what do you think happened to all his kung fu techniques?
Would he have been less effective with his insanity? Or would he actually fight better since he doesn't have so much weighing on his mind.
Maybe after Ah Bi died he went into a cave as a hermit and made up stories about being an undefeatable swordsman since his sub-conciousness is still plagued by the shame of losing to the Tian Xia Di Yi Jian.