Arabia: Ansar Warrior-Macemen, lower cost, no resource requirements.
Byzantine: I would not have a dromon as a UU becasue early on most sea units arent worth building. Rename Cataphract into Tagmata, it would be a better representation.
Comitatenses: Crossbowmen, +1 str, -25% melee, +15% cavalry, increased cost OR
Varangian Guard: Macemen, -15% vs knights, +15% melee. OR
Foederati: War Elephant, +1 move, -25% vs cavalry, +25% vs melee.
Egypt: Ptolamaic Phalanx: replaces swordsmen, +15% vs melee and cavalry.
Medjay Bowmen: replaces archer, +1 str or +2 first strikes.
Ottoman: Ottoman Turks- Sipahi: Curiasser, +1 str.
Bombard: replaces trebuchet, requires gunpowder, better city attack, +1 str.
Seljuk Turks: Askaris: replaces knight, +15% melee and cavalry.
Persian:
Sparabara: replaces spearmen, +25% vs archers.
Clibanarii: replaces War Elephant. +1 move, +1 str, -50% mounted, increased cost.
Russia:
Dvor Cavalry: replaces knight, +15% vs cavalry and melee. slightly increased cost.
Polk Infantry: replaces pikemen. decreased cost, -25% cavalry, +25% melee.