Set things up to be a 2 phase deployment.
Since you are open to Nanotech and Neurological mods, have it work like this:
Nano bots, controlled by neurological signals, produce a long, thin extension from the controllers hand. These nanites are going to have a conductive shell for the electricity to follow. They may or may not have some sort of filament trailing behind them. They launch and make contact to the target, creating a path for the electricity. If need be, a bit of extra effort may go into creating a path for the electricity to get to the ground.
Then, electricity, from an array of supercapacitors, discharges along the path created by the nanites. The amount of current will likely vaporize the physical path as the discharge happens, but that should be okay as the path through the air should already be established for a secondary blast, kind of like lightening following the same path on a secondary flash.
You are going to have a fairly short range, and burning up the mass of nanites is going to probably going to give you a limited amount of discharges. Also, your superhero costume should probably have really thick rubber souls and should not be worn in the rain.