supplied or equipped. The idea behind a militia is men of military age were obligated to serve to defend the state in cases of emergency. They were to keep military weapons and know how to use them when called. This is the only meaning I can see that makes sense in this sentence. Keeping and bearing arms on an individual basis does not lend to discipline, nor does it lend itself to control through government regulation, but it does save the state the expense of supplying the weapon while providing a member of the militia an opportunity to become proficient in its use. It also keeps the state free because the power of the gun remains with the people and not in the hands of the government or a professional military.
I live in Kansas. Up until I became too old, according to the Kansas Constitution, I was a member of the Kansas state militia - which included all able-bodied males within a defined age range. I don't believe I was required to keep or practice with a military grade weapon, however.
The Kansas state Supreme Court at some point ruled the right to keep and bear arms listed in the Kansas Constitution was a "collective" right, which means it was no right at all. So, Kansans voted to change the Kansas Constitution a few years ago to make it unambiguously an individual right.
[F]orce can only settle questions of power, not of right. - Clyde N. Wilson