QUOTE(Uleni Athram @ Feb 26 2017, 06:23 PM)

@SubRosa: Funny thing was, I was actually kinda confused whether the picture I chose was a Falcata or a Kopis. They just looked so identical! Heh. Looking at some of the Kopis now, I kinda get why they've used it as a cavalry weapon; the middle curves seem like brutally effective implementations for lopping heads when you're on a horse!
The Macedonian army had many elite formations within it. But the most prestigious and perhaps famous were the Companion Cavalry, led by Alexander himself. They were heavily armored horsemen, who specialized in shock (i.e. melee) combat.
Their opposite numbers in the Persian military were even more heavily armed and armored. After the Persians created their empire, their worst enemy often turned out to be other Persians, in the form of rebel Princes with an eye to killing whoever the current King of Kings was to take his place. Since these battles came down to Persian vs. Persian, and they hinged upon the leaders not only fighting, but being the one who lived, the Persian cavalry adopted heavier and heavier armor and weapons.
By the time Alexander invaded Persia their heavy cavalry was even more heavily armed and armored than the Companion cavalry. So the Macedonians really needed weapons like the Kopis and their lances to make any kind of dent (pun intended!), in that thick Imperial Persian armor.