[cabite]

What about this:

A swarm of non lethal drones equipped with 3D/depth cameras that collaborate in order to establish a dynamic 3D map of the terrain. A user consuming data from the swarm would enjoy a live "God's view" on what actually happens in reality, but through a 3D view displayed on a screen, very much like in Starcraft but without an artificial "fog of war".

This isn't a weapon of mass destruction nor a weapon in the classical meaning of the word.

But is this a weapon system, i.e. a system meant to ensure or enhance a weapon's function, such as targeting and guidance ?

[nexuist]

This already exists: https://en.wikipedia.org/wiki/ARGUS-IS

I think you would be hard pressed to classify cameras as weapons. No one is being harmed by the action of taking a picture - you would have to introduce a separate weapon, such as a missile or gun, to cause any damage, and those are all governed by existing regulations.