Cleon
Legend
And even here it gets adjusted - we can only adjust armor to fit races of the same size, I believe.
Worse than that. The "harness" in question was literally just a bunch of straps which support various weapons, badges of rank, and a few pouches for geegaws.
Martians don't seem to bother wearing armor - or clothes for that matter. There are multiple references to them using shields, but I could only find a single reference to armor in A Fighting Man of Mars:
When at my solicitation I was presented to her, she glanced first at the insignia upon my armor, and noting therefrom that I was but a Padwar, she vouchsafed me but a condescending word and turned her attention again to the Dwar with whom she had been conversing.
That sounds like the "armor" is just a glorified harness with little defensive value. I could find no occasions when a combatant got any protective benefit from armor - their isn't even any mention of them wearing helmets.
I haven't had a thorough check yet, but so far I haven't found any examples in the books of a Green Martian using more than one weapon at a time. In melee they normally use a "mighty long-sword" that are "long, straight, needle-like".
I've just remembered one weapon the Green Martians wield that doesn't appear to be Medium sized. They use spears that are forty feet long. Even if they're holding them in the centre that's a 20' Reach.
A Green Martian spear may be more like a lance in D&D terms though - they only use them while mounted in the books.
Also, Green Martians wield these spears with two hands. Tars Tarkas is holding one in both his right hands while charging John Carter when the two first encounter each other.
That might mean Green Martians can wield two-handed weapons with the arms on one side while doing something with the other arms (like handling reins, an off-hand weapon, or a shield), or possibly that "Green Martian Spear" is an exotic weapon they have a racial proficiency in.