The Rhodok's council thing. 1.How exactly do you enforce the rules against weapons without weapons. 2. A bunch of important people with rich friends with no weapons/heads of the enemy nation with no weapons, seems like a very stupid idea to not expect an attack during this.
1. The rules are only enforced once the council is over, presumably. In any case, "rules" and "law" in Calradia are little more than pretext to allow those with the strongest armies to do what they want to anyway. 2. The practice is pretty stupid, but perhaps the Rhodoks were not expecting any attacks, as the meetings could be held in secret or in areas well-protected, suggesting that Rhodokian intelligence had failed, or it was a complete surprise attack. Maybe even the guy with the weapon informed the enemies of its location, then rushed in to "save the day". The game is reasonably careful in showing that there are two sides to every conflict for the claimants, and that pretty much every would-be ruler is not above cut-throat tactics.
How bandits without horses are shown as having horses on the map, which allows them to catch up to you, and then you can't run away for whatever reason, despite the fact that you do have a horse.
You are thinking of deserters (though why they have them is still a valid question) and all bandit units except sea raiders have a chance of a mount.
Generally, when you encounter an enemy force on the map, you go to a parley screen before the battle begins and meet the enemy commander face to face. Presumably, after this both armies then separate before the battle begins and charge from a distance. However, why do looters and bandits do the same thing? They walk up to you, announce their intention to murder and rob you, and then withdraw (often on foot) two hundred yards away before the battle starts.
Maybe they're actually yelling at you from far away, and if you answered, you were also yelling back?
It could be a cultural thing, where two leaders meet on the neutral ground between two groups, issue their demands and once the demands have been issued (and rejected), both leaders return to their troops and commence the battle. So both you adn the bandits were away from your troops, then went back to them.
Why do ransom brokers randomly move from town to town? It seems like either staying in on place where their customers/suppliers know they can be found, or at least moving in a fixed, predictable circuit (e.g., people know that the Ransom Broker who covers Dhirim is currently in Suno, but will be in Dhirim in four days) would be far better for business, both letting manhunter-types easily find them and sell them captives, and allowing slave buyers or friends/family members to find them and pay them to buy a slave/free a friend or relative.
Is it possible that ransoms aren't all that common? Most counts/emirs/jarls are ransomed directly from the person who was captured, and most prisoners are just held in the dungeons in a town or castle until the lord sees fit to release them. The ransom broker probably makes his business solely off bandits that run around capturing farmers and the player. Not to mention, when you're associated at all with bandits (which, even if the bandits don't sell.to.him, are mostly what the player will be selling), you're not exactly in a safe occupation. There's plenty of reason to get to a town, do.business, then disappear without a trace.