I still don't understand what you're getting at. No two factions in Warband were alike, if that's what you're talking about? Nords were the only ones with throwing axes, had skirmisher cavalry(free javelins with no heavy lance), were the only faction with Polearm axes, their 1h axes were the best. Swadia had 2h swords, but only darts for their infantry, had Crossbows(for which they shared only with Rhodoks, who have a common cultural background in the lore), their cavalry were the only faction with greatlances. The only generic faction were Sarranids, who were a jack-of-all-trades faction, which by itself is a characteristic. Now in Bannerlord, all of the troops can get on a horse or pick up a bow and be as proficient as the class they looted it from. The equipment choices are gimmicks designed to give the impression of choice, but heavy infantry of all factions plays almost exactly the same now with no real quirks.
Yes, but this doesn't have anything to do with the class system. You could give the factions a unique appearance without gutting all customization.