Miezan numerals had been branded between their shoulder blades. A man in his late fifties had a one, he glimpsed a pair of twos and the rest were threes. Officer rankings. He’d heard Stygian slavemasters gave sets of enchanted irons to burn away the numbers and brand new ones when the purchase was made, to accommodate field promotions.

The Miezan empire is the very obvious pgte stand in for Rome, so I always imagine Miezan numerals as, well, Roman numerals. There is no reason to assume this actually corresponds to what Miezan numerals look like, but in this situation it has the fascinating implication that instead of making III the highest and I the lowest, thus allowing a very straightforward 'add one more I for promotions' system, the Stygians decided they'd much rather have magical branding irons that remove brands as a system.

(though the idea that a slaver society uses brands to mark slaves, whose main advantage is being hard to remove, and also simultaneously leaves magical-brand-removers around camp is still there no matter what Miezan numerals look like, so)