If you banged on a modern nuclear weapon for an hour with a 2 kg hammer, you'd have a sore arm. Soak it in warm water and take an aspirin.
If you sawed into one with a metal cutting saw, it would just quietly turn itself into a brick.
Nuclear weapons are designed to be both tough and delicate (meaning: they like to brick themselves) at the same time. An extraordinary amount of clever engineering across decades has made them this way.
Disagree on the just part. A metal cutting saw into plutonium wouldn't exactly be good for your health. So long as it sits there as a sphere it's not going to hurt you, but it's way down there on the periodic table where basically everything is pretty toxic. You do not want to inhale the dust!
Reminds me of this quote from XKCD What If?
> But just to be sure, I got in touch with a friend of mine who works at a research reactor, and asked him what he thought would happen to you if you tried to swim in their radiation containment pool.
> “In our reactor?” He thought about it for a moment. “You’d die pretty quickly, before reaching the water, from gunshot wounds.”