It's also a "life experience" thing. In the long-ago when I was growing up, a lot of police officers would have handled a grenade before. Would know how to unscrew the fuze assembly and discover the detonator was there or not, the TNT was there or not. And if it was "live", would take it out to an empty pasture and pull the pin and heave it far, far away. No fuss. Livens up a dull day.

I was Signal Corps, most assuredly Rear Echelon, yet I know how to handle and disarm a wide variety of US and foreign (mostly Soviet-type) weapons.