Greek swords

The Xiphos, without a doubt. It developed from the Mycenean bronze age sword almost directly. The Kopis may have had a bronze antecedent but I have not seen an example personally. I believe that there was a bronze single eged sword found in Northern Italy which was a singular example. I have never heard a specific time frame of development for the Kopis though it does seem to figure farily early in Greek pottery art. I'd imagine they were around but just not as popular as the xiphos in the public mind of that time. In fact the Kopis may not even be originally Greek it may very well have been a Thracian weapon in origin or at least derivation.

I am not exactly sure what you mean by the 'lakonian'. I am hoping you mean that particular sword carried by the Spartans and not the MRL Lakonian sword. MRL's sword is loosely based on a bronze miniature sword that was likely part of a statuary display. As for the Spartan sword it was a preferential development of a smaller xiphos. Nothing more, nothing less. Same construction and relative blade form as the standard sized xiphos.

I had noticed to that the kopis or machaira was usually in 'barbarian' hands (not necessarily Persian but Thracian, Phrygian or any other non-Greek antagonist). I have always felt that the kopis was derived from a more northerly Balkan or Central Asian(around the Black Sea region) culture. It is definitely not Persian. There is no evidence of it in the archaeological record or the pictographic scultural or painted evidence.

The Spartan sword became most prominent during the Pelopennesian War.

Greeks may not have esteemed swordsmanship but they were likely handy with a blade. They had the most advanced documented martial arts of the time dating back to the 8th century BC. These were boxing, wrestling and the art of pankration. These arts would teach the fundamentals on up to advanced concepts of timing and distance, footwork, as well as body manipulation. As to why the machaira/kopis was shown in barbarian hands is like I said...it was likely barbarian derived as a weapon.

BTW, there is no sword type one could justifiably call "a lakonia" (or laconia - the Cs and Ks are kinda interchangeable in anglicized Greek, since it's always pronounced hard, like K, anyway). Laconia, AKA Lacedaemonia, is the region of Greece where Sparta was located: thus Spartan citizens and subjects alike were called Laconians or Lacedaemonians after their homeland ("Spartans" referred to the citizens exclusively), their straight swords were of course Laconian xiphoi, and their characteristic style of terse, deadpan repartee is still termed laconic.