This LED ‘light sabre’ has been developed for use in crowd control. Evidently, the handheld device using light-emitting diodes to emit super-bright pulses of light at rapidly changing wavelengths, causing disorientation, nausea and even vomiting in whomever it's pointed at.
There has been a concern that LED applications could cause epileptic seizures, however, most people that are susceptible to seizures would react to flashing or strobing in the 15 to 20 CPS or Hz range only. If you consider reverse engineering, it is easy to see that a device could be created that could induce a similar non-lethal effect.
We have now taken LED to another dimension. Who would have considered weaponry as an application? As a specialist in market transformation, this took me by surprise. I had always thought of LED as a ‘weapon’ to combat energy usage in lighting, but this is a bit stronger use of the word!