There is only one weapon, and that weapon is intelligence. A
"transhuman" is a transhuman mind. Anything else is a side issue, a
technological party trick. Neanderthals with machine guns could not have held off Cro-Magnons with clubs... because the Cro-Magnons wouldn't be armed with clubs for long. Unless a nanowar is too fast and too deadly for any research to take place, the war will be won by the side with the better neurohackers.
I don't say "better AI", because then the war is won by the AI, period. Intelligence is its own purpose and has its own goals; even if superhuman intelligence is created by one side in a conflict, it will very rapidly become its own side as soon as it passes a certain level of intelligence.
A free nanotechnological society is dynamically unstable; any research lab possesses the resources to create either military goo or a computer with far-transhuman capacity. A nanotech society is supersaturated with the means of transition to the two stable states, death and Singularity. Such a society would not last long enough for legal issues to become relevant.
-- email@example.com Eliezer S. Yudkowsky http://pobox.com/~sentience/tmol-faq/meaningoflife.html Running on BeOS Typing in Dvorak Programming with Patterns Voting for Libertarians Heading for Singularity There Is A Better Way