Honour on the Battlefield

 Before engaging in battle, parley. "Hey, I promise not to use this weapon, in exchange you promise not to use that one."

 First note: wisdom is the highest virtue but faith is the foundational virtue. All honour requires keeping your promises. If you don't keep your promises, you are simply dishonourable. Treachery is irrational; if parley with you is a waste of time, it makes you weak and vulnerable. You don't want to make rational actors realize your genocide is their most convenient policy. 

 Second note: if you're at war, by definition there is no higher power to appeal to for arbitration. Contracts must be self-enforcing, as with the above. 
 An honourable country can and should know all about chemical and biological weapons, AI weapons, not to mention having as many competent assassins as they can muster along with no shortage of skilled torturers. Solely so they can force other countries not to use weapons by promising to not to use their own. "If you agree not to use laser weapons, we won't use landmines."

 An example of the perversity of strategy. The more vile the available tools of war, the more civilized the actual warfare can be. 

 Conveniently, there is no need for permission. You don't have to worry about how other countries conduct their wars. There is no need for a pre-war agreement. There certainly isn't any need for a global arbitrator or mass treaty. If you think other wars are being fought with the wrong weapons, you can simply negotiate different terms for yours. For example, to me the danger of landmines isn't landmines, it's incompetent Africans. The mine-layer will forget their own maps, and the new owner of the terrain has no reason to care if some serfs get crippled now and again, because he won't be held to account. If they weren't getting merked by old mines they would get merked by something else. I would stolidly refuse to be held to any "treaty" ""obligations"" regarding landmines. Basically, do not sign the Geneva Convention. It's retarded and traitorous.

 There's always the issue of total failure causing desperation and irrational moves. If you're going to be dead anyway, what use is honour? That's the thing with war against an honourable country. Two things, actually. A) you can surrender before you get to that point, because you're honourable. B) you can surrender before you get to that point, because you can trust them to not be dishonourable in victory.

 And, you know, you have all that nerve gas to set off if they try to double-cross you. 

 Of course none of this applies to Fascist countries. They have no self-control. They're like animals. It's questionable to suggest they're even literate enough to be able to meaningfully consent to a written contract, and regularly refuse to even try to negotiate one. If mortals hadn't degenerated in lockstep, the non-Fascist countries would be slicing through Fascist armies like knives through butter.