Yes so i was playing mount and blade original and i actually managed to beat all factions. Calradia is conquered by the kingdom of Nords.
I think the difficulty rating is calcucated over the whole game as i was playing at 52% difficulty for some time until the end, guess the starting difficulty was set too low, as it's registered as 38%. But i managed to beat the game in 1444 days
Guess when i got the best lordly armor i had an easier time mostly.
Also wanted to finish this game a little faster that is also a reason for the lower difficulty.

Now i will probably try playing warband.
Also screenshots from the ending of mount and blade.

https://imgur.com/a/sU9CDwT
https://imgur.com/hS3XepJ

Also what is up with imgur i used the ingame screenshots and it was just white when uploaded the bmp file so then i turned them into jpeg with painter and now it's viewable.

Yes i was mostly a marshall when i felt like it at end game and sometimes before i wasn't, but i could like have 200 army men in my own group at the end. Also everytime i took over someone that had a city or castle or many prisoners i simply recruited them as much as possible and mixed them with all faction soldiers. So i used bigger trained armies for taking over castles and towns with being marshall and nords lords helped me.
Also think i needed to bring up the trainer skill for upgrading my soldiers fast at end. Most used command was follow me and thanks to Artimetter he had a high engineer skill 8 and Nizar was just a strong soldier with good spotting, didn't have any other companions.
Also i was a 2 handed weapon player mostly, i used a steel shield when i was protecting myself from arrows and close i simply used a 2handed great balanced axe or something which mostly needed 1 or 2 hits to bring down a soldier also broke their shields very fast. Even though i had all plate and heavist lordly armor i was usually in such a position that i was killing many enemy soldiers fast while they were attacking my allied soldiers, the lordly armor did help very much to beat the game faster. Also used crossbows when besiegin and i did many headshots with it.

I had like 2 villages with a very high good relationship that offered me many recruits. Also towns i was buying the mercenary soldiers in taverns or whatever they offered me. I owned 3 towns which brought me good money but sadly i lost Dhirim during the swadia going at war with Nords.
In the end i needed to use army with horses to move around the map faster since when a faction doesn't have a residence you have to hunt them down and that part was kinda annoying. Swadia was easier to find with last lords since they would report if they passed an allied residence when nords already owned everything.