During the early history of ancient Greece there was a conflict called the Lelantine War. We know very little about the conflict, even if it actually happened, which is why I am tentative in ascribing it to a particular period. Both Herodotus and Thucydides allude to the conflict, with Herodotus telling us that Miletos and Samos were involved (5.99), Thucydides telling us that it involved the entire Greek world (1.15). Thus, such a war was present in Greek cultural memory, but we don't have many clues about it.

That said, there are some references to the conflict in our sources, particularly Strabo, in relation to your question. Strabo tells us that:

When differences arose concerning the Lelantine Plain they did not so completely break off relations as to wage their wars in all respects according to the will of each, but they came to an agreement as to the conditions under which they were to conduct the fight. This fact, among others, is disclosed by a certain pillar in the Amarynthium, which forbids the use of long distance missiles.

Strabo, 10.1.11-12 (trans. H. L. Jones, 1924)

As we can see, in this semi-mythical war there was a prohibition on the use of long distance missiles, i.e. bows and slings. Strabo seems to imply that this prohibition was agreed upon before the fighting began, and continued through the war. His reference to "a certain pillar in the Amarynthium" would appear to be definitive proof that such conditions existed in a past conflict. What's more, a fragment of Archilochus appears to refer to Euboeans only fighting with swords:

There won't be many bows drawn, nor much slingshot,when on the plain the War-god brings the fighttogether; it will be an agonyof swords - that is the warfare that the doughtybarons of Euboea are expert at...

Archilochus, fr. 3 (M. L. West, 1993)

Strabo's assertion of physical evidence to his claim, when coupled with this highly attractive passage, does appear to infer that the Euboeans fought primarily with swords, and that Chalcis and Eretria both agreed to fight primarily in this manner. However, our older sources that do reference the war, such as Herodotus and Thucydides, do not mention any such restriction. The novelty of such a restriction means that it would very likely have caught the attention of these writers, particularly Herodotus, and while absence of evidence is not evidence of absence, this is a load silence. Furthermore, Plutarch accounts a rather developed narrative from the conflict, the arrival of Cleomachus the Pharsalian, and his death (Amatorius 17). In his account, Plutarch makes no reference to any restrictions upon the use of certain weapons, although he does reference a monument erected in Chalcis' agora, but this monument was established in honour of Cleomachus, and there is no reference to Strabo's inscription.

It is my belief that there was such a restriction in place, but that it was not in place for the entire duration of the war. Firstly, it would be impossible to enforce this rule given the numbers supposedly involved. Secondly, it is highly unlikely that even if the rule was enforced it would have been adhered to. I personally believe that there may have been some form of organised duel between champions of both sides, similar to the Battle of Three Hundred Champions that Herodotus tells us about (1.82), and both sides agreed upon a restriction of missile weapons, in the name of "fair play".

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I am by no means an expert on this war, and there may be other sources that I have missed. I hope some more informed persons can further elaborate.

This thread originally posted by u/Hatlessspider might be along the lines of what you're looking for.