here below I will share
my solving to the castle lack of utility with a solution that, in my opinion, will
also contribute to improve some aspect of the middle/late game-play + will help factions/clans variety and uniqueness (in particular the 3 Empire factions that has the same roster units) with a
very simple addition that, probably, will cost few efforts to the developers.
The castles will provide to every owners the possibility to recruit (throw out the only notable of the castle named "Castle's Bailiff") not the simple noble units, but
a special/rare units different from each factions (even include the 3 empire factions in order to gave their roster a different feelings). This special/rare units (only 1,2,3 tier units) will be available only to be recruited by the castle owner and
in very few quantity (in less numbers then noble units couse has to be more rare). Tier 1 will be accessible with tier 1 infrastructure garrison of the castle.
Upgrading the following infrastructure will allow to have access to tier 2 and then tier 3 (or u can level up the tier 1 as usual with battle experience).
In addition, will be cool, if the AI lords that own the castle can recruit only very few numbers of them (cup limit like less then 10 for party)
while only One specific clan and his members will be able to recruit a bigger number of them (like more then 20 for each parties).
This clan has to be the closer to the respective factions with shares some affinities in battle style or Armour peaces as better explain below.
This way will help to make unique the way of fighting of Clans to give a bit more variety in fighting style of a faction and will make that clan emerge and be remembered among all others of the faction.
In my opinion will be cool to make also the clans of each factions visually distinguishable (as example all family members of a Battian clan have red color hairs / another family clan members can have to the face war painted and so on). This will help a lot the immersiveness of the game.
That said,
the player will have access to those units only owing the castle of the faction that can provide this type of unit and will be able to recruit them in a few numbers (or always take them as prisoners form another lords that has them).
Here is the list of unique/rare/special troop (that can be implemented with lore of the game) as suggestion and relative pictures:
1) North Empire: they are closer to the Sturgians and Empire luck or heavy hitter troop despite Sturgians. So this is the figure I thought: a heavy infantry units with 2 handed weapon with armour mixed with sturgian pieces.
Tier 1: Empire Axeman/Woodcutter
Tier 2: Empire veterian Axeman
Tier 3: Empire executioner
2) South Empire: they are closer to the Khuzait and will be cool to see also a mounted archer Cataphract to compete better with the closer heavy archer enemy cavallery.
Tier 1: Empire mounted archer/scout
Tier 2: Empire relay
Tier 3: Empire archer Cataphract
3) East Empire: they are closer to the Battanians and Empire luck or good javelins troop to face the guerrilla from the closer enemy.
Tier 1: Empire Velites
https://i.imgur.com/5vyIGhE.jpg
Tier 2: Empire veterian Velites
Tier 3: Empire mounted auxiliary
https://i.imgur.com/ojZCQXb.jpg
4) Vlandia: they luck of bowman/archers that remand me of Englang longbowman. Since they are close to Battanians they can have acquire the art of bow from their fians champions. This is the only factions i found out was better to only have a tier 2 unit (with the possibility of two different upgrades) and a tier 3 unit apart with no upgrade.
Tier 1: Vlandia bowman
https://i.imgur.com/1VuNL5g.jpg
Tier 2: Vlandia Longbowman / Tier 2: Vlandia mounted Yeoman
https://i.imgur.com/evMdNzx.jpg
Tier 3: Vlandia foot knights (mix of two handed weapon and sword/mace and shield)
https://i.imgur.com/X40ssK3.jpg
5) Stugians: girls power, Nothing to say. Everyone wants them and here You have the better lore to include them.
Tier 1: Sturgian swordsister (mix of two handed weapon and sword/axe and shield)
https://i.imgur.com/M0mbkG7.jpg
Tier 2: Sturgian shieldmaiden (mix of two handed weapon and sword/axe and shield)
https://i.imgur.com/cznaG1i.jpg
Tier 3: Sturgian Valkyrie (mix of two handed weapon and sword/axe and shield)
6) Khuzait: here a bit of lore will be needed. I thought maybe a sort of heavy hitter units with two handed weapons they miss. And that could be a sort of monk/zeloth soldier like Tibetan monks with bold hairstyle and face painted. Will be nice to be added by taleworlds a special 2 handed steel hummer for them that is missing in the game. Their lore can be related to be a sort of a temple protectors.
Tier 1: Khuzait white monk
Tier 2: Khuzait zeloth
https://i.imgur.com/PyyxZzi.jpg
Tier 3: Khuzait skullcrusher
https://i.imgur.com/0Z81Wub.jpg
7) Battanians: they are closer and worst/ancient enemy of the Empire. They hate them couse Empire has taken their lands and destroyed their religions/ancient traditions. To represent that I thought: a small group of extremists heavy infantry unit that can compete with Empire legionaries with heavy armour and some pieces of Empire legionary most iconic. The unit is hunting for Empire troops and they passed from hunting them down with guerrilla tactics to have learned to fight as Legionary does, with their own heavy equipment.
Tier 1: Battanian scavenger (mix of two handed weapon and sword/axe and shield)
https://i.imgur.com/0sM91ZO.jpg
Tier 2: Empire's headhunters (mix of two handed weapon and sword/axe and shield)
https://i.imgur.com/J1mXvVL.jpg
Tier 3: Emperors terror (sword shield and javelins)
https://i.imgur.com/kywyAQx.jpg
Aserai: I have nothing in mind for them right now. Open to suggestions.
Thanks for the attention hope my opinions will help somehow to improve the game. Sorry if i did some English mistakes I'm Italian. Sorry i had pictures for all of the troops but i m allowed to upload only 5
...
With love