Some people suggested me doing the Gladiator as a completely separate class of its own. But I think that would be redundant. I was even tempted to use the Champion archetype and just change the name to Gladiator because it kind of fits. but in doing so, I was leaving the rest of non gladiator fighters with no option but the Battle Master.
So I worked on the new archetype. I looked at some of the gladiators from previous editions. The one on the original 2E box didn't had much to choose from, and the prestige class from 3.x was too dependent on the crowd cheering up. I somehow implemented that in one of the features, but also added the ability to impress the enemies, in case there's no crowd around—no, the party does not count as a crowd!
So here it is, my take on the Gladiator of Athas, as a Martial Archetype.
EDIT: I just changed the previous Favored Weapon feature for the Pit Fighter feature, to make it feel more like the original box gladiator.