Even though he was in fact surprised and a bit shaken by the kid actually going for the kill, he was also very certain that the kid is still harmless. "Really? Your aim was pretty bad, though. Couldn't even hit me," he shrugged. "I mean, yeah, it's possible you've stabbed a lot of folks but I think it's unlikely." Why was he being so casual about this? Probably because he views Noah less as a threat and more as just another dumbass kid.