August and Neal both appeared to not recognize each other. Therefore how would August know that whatever he had in the wooden box would convince Neal? To him, Neal was just a petty criminal from the Real World. So whatever he showed Neal in the box had to be recognized as universally magical in nature. That’s just my opinion and this show has a tendency to screw with your head. That being said, even though it may have been a universally recognized magical item, Neal could still have a connection to whatever it was and August just didn’t know it.