Microwaves are one of the realities I mentioned. The "Riot control" type system exists, at least in prototype form - a microwave transmitter using a dish antenna mounted on top of a truck for focus. It makes people feel like they are being burned, oddly enough!
Apparently it's not very effective even through thick clothing, and rain attenuates it to near uselessness.
I'd not like to think of the effects on peoples eyes, or anything metal a person had, that happened to be resonant, if they were close to it in dry conditions.