Arms merely means a weapon. And yes, Gov’t cannot restrict such. Having a weapon is not against the law. If I choose to use a slingshot, sword or super soaker, so be it.
That said, no government can pass laws outlawing insanity.
OTOH, a squirt gun is a toy, not a weapon, and a temporary public ban on protesters carrying them in downtown Tampa during the RNC convention is not something that goes against the right to bear arms, nor the right to protest.
But you know that, right?