This was such a fun and clever way to test Gon and Killua potential and what type of fighters they are. Chairman Netero being the head of the Hunter exam... he was Intrested in seeing what made those two get this far curiously . Killua demonstrated that he has battle experience and how lethal his style of fighting is. Netero knew Killua was from a member of a family of top deadly assassins and Gon who may appeared simple minded but who seems be an honest young man. Killua who may be the same age as Gon but was already able to do things such as Assess an Opponents strength, immunity to poisons, Master of the dark after image technique, has an awareness of battle tact, and has a high pain tolerance due to his upbringing. Killua knew Netero wasn't no pushover, and he wasn't taking them super seriously. Killua who can especially early on hates being toyed with knew the only way ima get that ball if I try to come at him with seriousness to kill. Instead Killua just said Eff it.. its not worth it but he was pissed lol... Gon refused to give up but before Killua leaves he mentions to Gon that they could never get the ball at that rate ....He hasn't even used his right hand or left leg. Gon didn't care about getting the ball anymore "I want to get him to use his other hand" lol.
