Being an Ancients minis game with a comparatively short period and geographical setting, Dux Bellorum has fewer troop types than you'll encounter in a lot of other Ancients games (De Bellis Antiquitatis springs to mind, probably as its one of my favourite games). That's one of the reasons I like rules to be tailored to specific time periods rather than generic sets spanning 3000BC to 1485AD, as we used to say: War Games Rules 3000 BC to 1485 AD ... you can really try to capture the essence of a period by limiting the troop types, odd as that sounds.
My take on the period is one of simple tactics and basic equipment styles, making Arthurian warfare (and other British Dark Ages) pretty distinctive in its simplicity.
In DB we have....
COMPANIONS: The tough guys, the personal bodyguard and household troops of the warlord. May be Mounted or Foot Warriors/Shieldwall. They have higher stats than other troop types, but each army only has one such unit. RIDERS: Medium cavalry in most wargame parlance - riding towards the enemy throwing javelins at short range (counting as close combat in the game), and closing with swords if they can gain an advantage. Expect no Charge of the Heavy Brigade! May be Ordinary or Noble, the Nobles being that touch better. WARRIORS: Offensive infantry (they like to charge in, as opposed to liking Bernard Manning), prone to make Uncontrolled Charges whether you want them to or not. As with Riders, they can be Noble or Ordinary. The most common type of foot troop in Early and Middle armies. SHIELDWALL: Defensive infantry (hmmm, haven't thought of a gag for that, have I?); harder to hit than Warriors but less likely to hit anyone else. As above, may be Ordinary or Noble. More common in Late armies and also with the Late Romans/Romano-British. SKIRMISHERS: Foot or Mounted, both are ineffectual until you work out the best ways to use them. More on that at some point! May be armed with Javelins or Bows, which naturally enough have different ranges (Bows also includes slings and crossbows should you be that way inclined). BOW (And CATAPHRACTS for the Late Romans): Rare troops, packing more punch than Skirmishers and Riders respectively. CHARIOTS: Optional troops for the Early Irish and Picts; I have seen no evidence to convince me of their use, but who am I to deny your using a nice model in your game?
Apart from for missile weapons, there's no distinction between different weapons or armour; I've factored that into the troop type and Ordinary/Noble designation. There are plenty of extra options for purchasing Javelins, Hurled Weapons, Dismounts, and so on, to allow you to shape your army for your personal take on Arthurian warfare.
Some point soon I'll post about stats, which drive the mechanics of the game, and on the differences between Nobles and Ordinary troops.