There may be other ways to address the problem than banning the weapons entirely. When things are expensive people seem more likely to engage in them out of necessity than convenience. But when things are cheap people become more careless about employing them. While it is desirable that in a situation where you are already fighting a war and have no choice about it you have the best weapons, and the highest chance of victory, it is not necessarily desirable – in terms of thought that is put into employing violence as a tool to resolve a dispute – that before the war you have access to those things.

While it is madness to suggest that in a war people will not use their most effective weaponry, the relative costs of war influence who is going to become your enemy in the first place and the scope of the wars that you will fight. Consequently as the technological disparity increases, and the cost of war against any particular foe decreases, it becomes more important to enforce greater discretion in the use of those weapons by other means - and in some cases it would naturally follow that if you really are enforcing greater discretion in the use of weapons there are some situations in which you do not use them when you otherwise would.

Simply because you have a weapon does not mean you use it in every case.