1 - The article doesn't define the militia (US code does, rather broadly, although of course its much easier to change ordinary law than it is to change the constitution).2 - The section does give the federal government the power to arm the militia and to govern them should they be employed in the service of the federal government, but it doesn't say that they will be, and they never have been) exclusively, or for the unorganized militia (see the Cornell link above if you don't know how that's defined) even normally, employed in the service of the federal government.