You know what would be useful?

[Apgad]

I'm pretty sure the response to this will be "It's hard-coded", but I'll say it anyway.

It would be really useful if experienced units could be re-trained as new units, preserving their chevrons. For example, I've currently got a few 3 silver-cheroned units of Lybian spearmen. Now that I have Kart-Hadast's reforms, it would be nice if they could become heavy Lybian spearmen.

The same could occur for other factions with or without reforms. You could have a regular Makedonian phalanx that's been with you from the start, steadily racking up the kills and chevrons, and then suddenly you can recruit reformed phalangites. It would be nice if this very experienced unit could be fitted out with the latest armour and sent back to the front line. Perhaps levy pikemen could gradually make their way up the phalangites ladder, accruing loot on their way to buy more advanced armour.

Elite veteran Camillan principes could graduate to Polybian principes, and then on to Marian legionaries, keeping their chevrons as they go.

Obviously you couldn't have Hellenic skirmishers upgrading to heavy cavalry, but where you have similar fighting styles it would make sense (conceptually speaking) for an experienced unit to have the best equipment available.

[bovi]

"It's hard-coded".

[Strategos Alexandros]

Role-play it by disbanding them and training the new unit. If they have to be trained further away say they went to collect their new equipment.

[Hooahguy]

or you can use the create_unit cheat to upgrade them with the proper chevrons and upgrades

[Apgad]

Role-play it by disbanding them and training the new unit.

Yeah, but that loses all of the experience that unit has gained. Perhaps it makes sense to lose maybe 1 chevron, to account for getting used to new, heavier equipment, but I don't want to disband a 3 silver-chevron unit for a single bronze one.

Here's another idea - if there is a settlement where a lot of units have been disbanded, it would make sense for units trained there in the future to get an experience bonus. This could reflect the re-enlisting of veteran soldiers.

But, as they say, "it's hard-coded"...

Just a thought, though