My attitude about just about anything that is "dangerous", is to have stiff penalties for those who misuse those items. Machine guns, bazooka's, flame throwers, suppressors, whatever. If you can afford the going price for it, it's yours.
Now, if you take your RPG to the movie theater and waste a lot of people, you should be executed in an expedient and preferably, grotesque manner.
If you're a burglar and you're caught wearing body armor so the police or homeowner has a harder time stopping you, then you probably shouldn't see the light of day for a significant length of time. Likewise if you're wearing body armor while you hold up a convenience store.
It's not about the item you possess... It's about accountability for what you do with it. And if you misuse the public trust and commit mayhem, then they should come down hard on you. If someone wants to spend 35 - 40 years of their life in prison, or forfeit their life altogether, then go out and do something stupid. But it's gonna cost ya.