That opposition was not complete. It was thought there should be a standing army sufficient to respond to external threats with the help of the State's armies, and that it should be large enough to step in and shut down martial conflict between the armies ("militias") of any two states.
It was, indeed, necessary to the security of a Free State. It had to remain, ultimately, under control of the Civil Authorities. and thus, remain "well regulated" (controlled). The rest of that is that the ultimate control over the possibility of that Standing army being used to impose tyranny on the citizenry was in the overwhelming numbers of The People, who by the force of their individual arms could resist and quell such usurpation, even in the absence of martial training.
Thus, A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed. enshrined the individual Right to Keep and Bear Arms as sacrosanct.
At that time there were no limitations on the tools of war which could be possessed by the individual, save those of simple economics. If you could buy one, you wanted to buy one, you could.
There is nothing in the Constitution which authorizes the expenditure of monies from the Federal coffers for the purposes of charity.