Board Thread:Questions and Answers/@comment-26047416-20150127010029/@comment-5780397-20150318213456

But it is unlikely he's ever had a chance of feeling Zeno's aura, since every time he sensed aura, he immediately associated it with Illumi, and Killua himself made clear that only Zushi and Illumi gave him that feeling. Plus, even if that was the case, he had no way of knowing the name of the ability.