Only individuals have rights. Governments, which include the military and police divisions thereof, have powers. In some times and some places, police did not have the power to be armed with firearms. In Great Britain for instance, until they started disarming the people, the "Bobbies" rarely went armed, although supervisors could bring arms to a scene if necessary. I'd at least say that the police should have to power to have any arms denied to any law abiding citizen. Of course since "shall not be infringed" says that citizens have the right to have any kind of arms, that need not a be any great restriction.
I understand the distinction. That's why I was careful to use the word 'need' and not 'right', thought 'power' would have been more accurate.