@JERUSALEM
Guess what faction I've had the privelage of having some awsome battles with today? Georgia. And guess what? They have some of the best heavy cav in the game. Monaspa Lancers, Eristavi, Tadzreuli, and a Heavy HA Monaspa. These guys are killers. Giving Georgia a cataphract unit is simply overkill. They have a very strong selection of heavy cav, they don't need anymore.
This is not the only faction like this. The Ghorid Sultanate and Ghazni will be the same too. No cataphract cav. They were specialists in heavy cavalry - but no horse armour. Same for the Georgians, Armenians and Rajputs. None of these faction have cataphracts - except for their generals.
And here's a little screen just for you and Tadzreuli
Georgian Monaspas and Tadzreuli cavalry put Turkish levies to flight
Another one:
Another:
(sorry about the english banners)