It's fine and good to limit such devices, but without an Amendment prohibiting WMD, biologicals etc I cannot agree. The founder's did not limit what weapons may be held by the citizens; they didn't limit weapons to only the army or militia; they didn't limit weapons to SELF-defense purposes only; they didn't limit the weapons held to be "discriminating" weapons only or otherwise create distinct classes; they didn't limit weapons to anyone by virtue of age, wealth or any other exclusionary tactic.
And should the last situation you described occur, the armies will be able to slaughter the civilian population regardless - not too many individuals could begin to have the necessary firepower to protect themselves. But the THREAT of having a small nuke might stop them and prevent that very situation from happening. A well-armed population is what kept the Japanese from invading the mainland in WWII. If they thought we all owned a P-51 Mustang maybe they wouldn't have attacked in the 1st place.
What I am arguing is that these words exist in a context of reality, and that this reality is that your rights are bracketed by mine. Nobody's rights trump anothers, and therefore we must analyze the ability of you to wield a weapon to positive effect without damaging my rights.
It is for this reason I have analyzed the indisriminate nature of the various forms of weaponry. Those that are excessively indiscriminate cannot be useful to you within the context of the failure to violate my rights.