> You might be tempted to say "what about a missile shield?" but such a thing allows the owner to act with impunity with levels of violence we arguably haven't seen since 1945.

I would still say "what about a missile shield?".

If a missile shield is a weapon, because of its affordances, then any object is a weapon. And while that's marginally true I don't think we get anywhere by entertaining category errors.

If something enables aggression, because it makes counter attacks unreasonable, that seems like a fairly nice thing to have more of, in a world where destruction is far too easy and construction is fairly hard.