sabers first reached Arabia in the 7th century via the Khazars
they where available to all factions in the age of the crusades, but
mostly used by cavalrymen and were slightly less curved
than future versions would be...
you can also combine infantry crossbowmen and archers together
for all factions, in one cooperative unite, as documented by historical sources
Ayyubid mounted archers also included mounted crossbowmen
regarding diversity, here are some ideas
for more items, units and tavern mercenaries...
as I said before, you don't need to use just the crusader way of expiation models,
adding items from Anno Domini 1257, and many other mods,
works great with them and adds more diversity