Had Nick wanted to hold him, he would have had no trouble doing so. He didn't feel it was in the youth's best interest to try to physically detain him. So he put up no resistance as the boy spun his way out of his grasp.
The kick to his midsection was unnecessary, but again, Nick tried to sympathize with the boy in his current state. It wasn't a hard enough blow to even make him double over. The threat of the sword was met with little more than amusement, particularly since he looked like he was trying to become a part of the tree's trunk, though his kept the emotion hidden. He needed to calm the boy down, not make matters worse by laughing at him
"It's alright." Nick put his hands up in a display of surrender. "I'm not going to hurt you. I saw you running from that man and just wanted to make sure you were ok."
He slowly reached his hand into his inside jacket pocket, pulling out his wallet and flipping it open. "See, I'm a cop." It didn't matter at the moment that he wasn't technically a member of the City's police force. Although the changes to his badge still had him puzzled. Perhaps, once he settled in a bit, he would have to take a trip to the station. See what was what.
"How about you put that sword away, and just calm down a bit. Then you can tell me what that man did to scare you."