Prior to the Geneva Suggestion, was it ever normal for militaries to poison their weapons? And if not, why?
Like I understand that such dishonorobru tactics would be avoided by certain groups or between certain enemies, but these weren't always the case. Plenty of militaries did all sorts of horrid shit to guarantee victory, and if you could make your arrow rain so deadly that a scratch kills the target just as dead as getting impaled through the chest, that means you can equip your bowmen with lighter arrows and weaker bows with longer effective range and higher ammo capacity.
I can understand why they might not have poisoned melee weapons since something fast-acting enough to make a difference that was cheap enough to issue to an army was likely hard to come by, in addition to how much of a pain in the arse it would have been to reapply poison after each cleaning and how much of a liability a poisoned blade is. Poisoning your swords and spears would more likely have either needlessly killed captured soldiers if you won and got you sent to the asbestos mines if you lost.