Essentially, a Paladin. It would be completely identical to the paladin in function, and thus either the Commander or the Paladin would never see any real use.The UU for the Khazars should be the Commander, maybe it could be a heavy cavalry unit with less melee armor but more pierce armor and an attack bonus versus archers/cav. archers? Just tossing ideas around. It's cost could be:
55 Food
90 Gold
...and it would be trained at the Castle.
Overpowered, especially 1 and 3.The Khazars team bonuses could be:
1.All cavalry(and cavalry archers) cost -20 gold in the Castle Age, -35 gold in the Imperial Age
2.Houses have +900 HP so that they are harder to destroy
3.Scout Cavalry, Light Cavalry and Hussars(including the starting scout) have +10 HP and +2 attack, as well as +1 melee armor/+1 pierce armor when Bloodlines are researched at the Stable.
Paladins costing less gold than an arbalest is crazy.
The Scout Cavalry line is balanced as it is. It also sounds like it can defeat loomed villagers in dark age, which is also overpowered.
The idea of stronger houses is interesting though.