I spoke at length with Renshi Desmond L. Diaz about the subject for two reasons -- one, he's my go-to martial arts expert (5th dan Goju-Ryu), and two, he's my nephew. To fight crime on the streets of my unnamed city, he suggested Krav Maga.
Krav Maga is unique in that it's designed to be taught and learned quickly. It's blunt strikes and counter-heavy nature was intended to make ordinary citizens into effective fighters for the conscripted war effort. The Israelis train their soldiers in Krav Maga, and when you consider that 2 years military service is required of every citizen, you don't want to meet too many Israelis in dark alleys.
In the recent "Batman" movies, Krav Maga is the style Bruce Wayne uses to dole out brutal justice on the streets of Gotham. These days, Krav Maga is more widely used, taught to military and law enforcement alike, which is perfect for my "could-be-anybody" vigilante.
I also asked my nephew what weapons my hero would need to carry and he broke it down in three words: blades, staves, and guns. Personally, I don't want to have my hero carrying guns as it doesn't fit the personality I want for this guy, but as for blades, I like the karambit.
The karambit is a Filipino weapon that was originally used for raking roots and threshing plants. In proper hands it is possibly the deadliest knife available. The curved blade was inspired by the claws of big cats (tigers, panthers, lions and such). It's lightweight, easy to conceal, and as shown by the video possesses a certain degree of up close and personal bad-assery. Batman would be proud.
As staves go, I like escrima sticks. A friend of mine trains with them and his giddy approval is contagious. Again, they go with the easy to conceal, easy to carry, and in the proper hands, can be a gleeful tool of attitude adjustment.
So the personality I'm seeking to craft for my hero is one of an up-close killer of killers, one who deals with these people in a manner suggests that they have done something to him personally. And who knows, maybe they have...