Since you concede that the nature of arms have changed since 1791, we need to pass a new constitutional amendment in order to define arms more specifically.
Maybe, or maybe we can simply use the logic and common sense of the inherent bracketing of rights as I have described them. However, if you were interested in a more precise amendement, I would recommend you use my discrimination arguments above.
The discrimination-test will allow for individual possession of laser, plasma, and other directed-energy small arms that the present interpretation of the amendment may not allow. The courts are likely -- at present -- to deny possession of laser pistols to the common man, and I find this to be an abhorrant future probability.
When lasers are outlawed, only Klingons will have lasers.