I demand juicy details. The juicier the better.
If you want juicy details I think I can give you info from a post that was made long ago. Note it is very long.
I called my idea for a byzantine based faction the Trebizand Empire
Trebizand Empire who are the remnants of the Calradian Empire. Their capital is the city of Trebizandum or better known as Justinianople after the Calradian emperor Justinian who had converted the Mount and Blade verse version of Christianity and made it the official religion of the Calradian Empire during its last century. Justinianople is based on the Byzantine Empire's capital Constantinople which had resisted sieges for over 1000 years until its fall to the Ottomans in 1453 (the fourth crusade doesn't count as they captured the city via the sea walls) and as a result Justinianople is THE hardest settlement to capture. It has two lines of city walls which you have to capture separately. the outer wall would have the standard amount of town garrison of 300 but the inner wall has a garrison and the inner wall towers that overlook the outer wall. Also when you try to capture the outer wall you will be exposed to archers from the inner wall. When you finally take the inner wall then you have to fight an 800 strong army that are in the farmlands that are just before the streets. When you take the streets then you have to then besiege the citadel which is basically a fortress inside a fortress city. Once you take the Citadel walls then you finally fight inside the great hall then the city is yours. Taking this City would REALLY, REALLY, REALLY SUCK as unless you are using cheats, you are likely to lose every one of your soldiers.
The army of the Trebizand Empire is nothing to dismiss. Note I am use medieval 2 total war names. The troops of this faction are based on the Komnenian Byzantine army. Trebizands are capable of recruiting people from most of the other factions to serve as special mercenaries that when fully upgraded can be really powerful. People recurited from the Nords, Vagiers, and Caledonia become Varangian guards, protectors of the Emperor who wield two handed axes. Recruits from Swadia, the Rhodok Leauge and Bertonia, become Lakitons who are western style cavalry. Recruits from Kherigts and Sarradins can become horse archers. At first the horse archers become Skythikons which are lightly armed and armoured but can move really fast, but eventually they become Vardariotai who are well armoured for horse archers, armed with powerful bows and arrows and are very capable in hand to hand combat. The Vardariotai are rival units to the Khergit Veteran Horse Archers.
The native Trebizands are nothing to be shy about. Even though they seam old and outdated they are still hugely effective. Their infantry are the well armored skoutatos who are armed with spear and occasionally glavies. Their archers are lightly armoured but use powerful war bows. There are guard archers who are as well armoured as the infantry and are very skilled in hand to hand fighting making them very good for defending castles. However the best native Trebizand soldiers are the cavalry. Their elite heavy cavalry unit is the Cataphract a heavily armored horseman armed with lance, shield, axe or a mace and rarely a powerful bow and a large bag of khergit arrows. These really strong horsemen are comparable to the Swadian Knights and Sarranid Mamlukes.
The Trebizand Empire may sounds overpowered, however wars against the Sarradins and more recently the Kerigits have made the Trebizand Empire fall into a state of decline so by the start of the game they have only a little bit of their original territory comprised of only 3 towns (including the captial) 5 castles and 8 villages. However their powerful military and strong economy ensures that they are still a major influence throughout Caldaria. They do well with the Vagiers, Nords and Rhodoks, however there is a state of hostility between the Byzantine based faction and both the Kerigits and the Sarradins mainly over lost territory. Also in recent years tension is being to rise between the Trebizand Emperor and the Holy Swadian Emperor Harlaus as between who is the true successor of the Calradian Imperial Emperors. Also the had been a schim between the churchs of Trebizand and the Papal State of Zendar which is starting to heat up the cold war between Swadia and Trebizand. The current pope Alexander IV, favours the swadian Emperor Harlaus. However there is a rival claimant to the papacy named Cardinal John who is a cousin to the Trebizand emperor. If the player helps John to become the next pope, John would restore relationships with the Empire of Trebizand and would begin supporting the Trebizand Emperor as the true heir of the Calradian Empire.