"Now you'll die a few days from now!"

I love it

Briefly

Yes, that would work. You would fire the prettiest blue "lazer" in all directions, then everyone in the area would die a couple of weeks later.

Clearly it's meant to be a grenade. Make it whole, throw it or roll it into a room, they can deal with the consequences as you make distance.

You joke, but:
https://en.wikipedia.org/wiki/Nuclear_shaped_charge?wprov=sfla1
https://en.wikipedia.org/wiki/Project_Excalibur?wprov=sfla1

Basically pointing one of these at someone. https://en.wikipedia.org/wiki/Fission-fragment_rocket