No, seriously. This is a pack mentality in action. I think we will be seeing more of this kind of thing. So, who wants to teach me to swordfight?
You could take up fencing to get some of the basic moves. There are some books on knife-fighting you could get at gun-shows (the Marine manual on knife-fighting and close quarter fighting has some interesting moves). I've been carrying sharp things since about 6th grade (growing up in New York) and from what I've seen the best ideas seem to come from the Marines, although the Philippeans has developed a very sophisticated system
As far as pack mentality, back in college I came across a pack of about 5 teens hassling an old guy in a NYC subway station. I had a 5 inch knife on me at the time, and I managed to convince them to go away. Yes, they each knew they could, as a group, take me. They also had total certainty that I would kill the first one to come within reach of me. Nobody wanted to be first...