Pariston is not the 'combat' type as it were, however that does not stop someone being 'strong' in this Manga. I'm convinced that Pariston is either a manipulator or a Specialist, and probably has a Hatsu that doesn't require any hand to hand fighting or weapons, or anything like that. When he say's he isn't strong I don't think he's lying, he is talking about his physical capabilities, but his rank as a Hunter and Netero's interest in him (Someone who doesn't respect 'weaklings') lead me to believe he has a dangerous and likely OP Hatsu. Judging by his character, it's probably something similar to mind control, illusions, etc, that seems like his style. Then again if he is a specialist it could be absolutely anything, so before we know, we can't possibly judge this fight.