Just thought I'd share something on this, as I think that this is a unit you should include in the mod (likely only one unit)
Spoiler Alert, click show to read:
Reading what is above they would seem to be a good unit for Abbasids, and perhaps for others as well (it says that the Mamluks carried on the tradition after the fall of Bagdhad), they could be a crossbow hybrid similar to the Latin Armoured Crossbowmen good with crossbows and good with swords. It also is pretty clear on some clothing, they seem to have worn some sort of distinctive trousers and cloth girdles (sashes?), I also seem to remember something about them wearing the same colours as the Assassins, they wore white and red robes.