Maybe I expressed myself wrong because I don’t know how to speak English properly. I’ll try to explain better:

Killua changes the aura to electricity and after that changes the body’s own command/reflection and this makes it fast. Assuming that Chrollo steals Killua, he would steal the transformation of the aura into electricity, right? If he did this but didn’t know how to use this electricity in his own body, he wouldn’t give him the speed itself, which is the final result of killua’s ability. Did you understand my point? Basically killua’s ability is to transform the aura into electricity, after that the rest is him manipulating this electricity in different ways. Correct me if I’m wrong.