"Felons" and "criminally insane" people are in jail (if those words mean anything). No, of course they should not be allowed weapons; this would make it difficult to keep them in prison.
"Unskilled" people with weapons should take some classes or something. It's not clear what you want the government to do about them, or how the government would define "unskilled".
That's a start.
Maybe then, EVERYONE will get out alive.
A life is a terrible thing to lose.