Having pants and/or a shirt on apparently does qualify you for a point or two or armour, AFAIK. Hats were worth an extra one IIRC. If the unit has shields and good helmets - like the Gaesatae nekkid dudes - then that alone qualifies them for a decent rating.

Although I'd rather the "has pants on" armour points were applied equally across the board. Assorted barbarians get it, but various Easterners in their trousers and thick kaftans to keep the inland winter cold away don't...

Also Eastern slingers having 9 melee attack whilst having only 3 range attack
There's good reasons why most EB missile troops have low base attack values at range; doubly so for the AP slings (the best ones - the Balearics - top at 4...). Although I'm not entirely convinced those of the assorted horse-archers are entirely "on par" with their infantry colleagues. Anyway, 9 is a pretty standard EB attack value for guys with daggers - indeed bit on the low side. It is a very fast and handy weapon after all. Alas, it also has a rock-bottom 0.04 lethality value, to the 0.1 standard short swords get...