I did this as part of an art trade for a friend. It was going to be an illustration for a history book.
Originally he just wanted a charging centaur armed with an axe. But I love history (I was a history major in college before my ADD kicked in and changed my major,) so I tried to make the details as historically accurate as possible. (I realize more than likely no one will notice, but I would and I'm sort of anal about historical details.)
So I searched through history texts to find about Greek weapons. Swords, spears, bows, javelins, even slings, but no axes. (Before someone mentions the Labrys, the double-bitted axe of Minoan Crete, I've found that this was mostly a ceremonial object and not used in warfare.) So I've armed him with a Persian war adze. I figured he picked it up as a war trophy. These were made with a forged iron blade and a cast bronze socket poured in a mould around the blade.
His helmet truth be told isn't exactly historically accurate. When I did the original sketch he wore a traditional Corinthian helm, but it covered too much of his face. So I eliminated the nose guard and opened it up a bit. Since each of these helmets were individually crafted, there was a lot of variation.
I debated on what type of shield he would carry (and what blazon would be painted on it). Obviously, he could not fight for Athens, not after what Theseus (the legendary founder of Athens) did to their forefathers. So, what else would they fight as but cavalry? And Macedonia had the best heavy cavalry of the ancient Greek world. As a result he carries a Macedonian shield. Ancient Thessaly was known to supply troops of mercenary irregular cavalry to various cities, including Macedonia, and Thessaly is also the traditional home of the Centaurs.
So as a result he is an mercenary irregular cavalry trooper from Thessaly fighting for the Macedonians in this little scenario of mine. (If you had the patience to sit through my description, I thank you.)