Still, in Lucas's case, her weapon CAN'T BE PARTED from her. What do you suggest gets done in that scenario
What I suggest is that governments get at least as suspicious of her as they would of a kid with a gun that she couldn't get rid of. Not being able to get rid of a gun is a fantasy element, but it makes the kid more dangerous than one with a normal gun, not less dangerous. It is entirely proper for a government to see her as a potential threat and act appropriately.
If you've been around Sailor Moon fandom you'll know that there is a common alternative interpretation of Crystal Tokyo as a dystopia where Sailor Moon forcibly purifies people in the name of fighting evil. There's a reason this interpretation is fairly common: people with that kind of power are dangerous. Vigilantes especially.