Whose arms?
Who selects?
If the state chooses who participates, and owns the arms used, then they’re not “the people” and no “right” is involved - they’re agents of the state using state-owned equipment, exercising a state power.
Who cares?
There's a member of a well regulated state militia. That person is carrying a weapon. The federal government may not infringe that person's right to keep and bear that weapon.
The second amendment doesn't state that the weapon must belong to the person. The second amendment doesn't state who that person shall be or shall not be. The second amendment doesn't say what the arm shall or shall not be.
Militia member. Gun. Protected.