Of all of Jin Yong's protagonists, Wai Siu Bo had the weakest martial arts. His skills are not even a drop in the bucket compared to those of most other Jin Yong protagonists.
That said, perhaps his martial arts are a bit underrated?
Though he would not last long against any elite fighters, it appears that he is good enough to take care of himself against ordinary-level fighters. He's not going to win many fights, but it appears that he does have enough skill to protect himself as long as he does not run into anybody too powerful.