Despite years of fog created by the NRA and right-wing organizations, that isn‘t very complicated; for the purposes of forming a state militia, you‘re entitled to keep and bear arms. Obviously, those would have to be the kind of use in arms since 1791, when the Bill of Rights was passed, the musket, the wheel-lock, the flint lock, the 13th century Chinese hand canon. Stuff like that.
Then, following his logic, "freedom of speech" and "freedom of the press" does not extend to electronic and broadcast media.
"arms" includes handguns and semi automatic weapons just like "press" means Cable, Television and Internet news.