His master said that all spirit masters have the problem of the starting point, where they need to build up their strength by taking weaker monsters in. As such, their beginning abilities are always weaker than their later ones.
But if San builds his strength with the weaker Blue Silver Grass until he becomes strong enough to hunt the strongest ones, he can make a "perfect" build with the Clear Sky Hammer and all rings taken from the most powerful monsters. As such, even if he met a similar level spirit master, he would be stronger since all the rings of the Clear Sky Hammer would be of extremely powerful monsters.
AFAIK Tang San as a "twin" cannot use both his abilities at the same time. So in his case he will improve one, then the other.