Well, yes, Kha-Belekh wasn't the most powerful demon when he seized power; he was cunning, but let's say that the princes of Shio at that time – Azkaal or Ariban, for example (if you're familiar with the plot of the sixth game, you know who they are) – were much stronger than Kha-Belekh. But all these princes and lords were at odds with each other, and the War of the Eclipse had also weakened them. In general, almost all of them died, and the future Overlord took advantage of this. And yes, I know that the devil there is essentially Urgash; I meant the Supreme Demon, but by the way, apart from Heroes 5 and Clash of Heroes, I haven't heard of any high-ranking demons being called devils in any other project related to Ashan. But yes, from the descriptions of devils, it follows that they lead the legions of Shio into battle. By the way, yes, it's a classic, but still a rather interesting name.
In general, I'll think about it; maybe we can adapt the names of the units to fit some kind of destroyers and ravagers, thereby separating them from the heroes of their faction. But for now, I don't know – I'll add your suggestion to the list of ideas.