Does anybody know anything about how the combat system actually works? I have a number of ideas to promote more warfare and combat, but I don't want to suggest anything that's actually already implemented and I just didn't notice. Particularly things regarding terrain, etc.
Most of the knowledge of combat is just speculation, but some things have been said. There is no rocks-paper-scissors, so a spear is always better than an axe, and a crossbow always better than a shortbow. That is for sure.
More experienced soldiers have higher morale (are harder to rout), and are more effective in the use of their weapons. A soldier with 100 experience and a broadsword will be much more effective than one with 0 and the same equipment. Much higher than if they both had axes, for example, as there is less room to improve with such a crude weapon.
Primary (halberd, mace, longbow) and secondary weapon (short sword) are counted together in melee combat, so your troops attack with both at the same time, and don't have to choose between them.
The following is my own speculation:
From what I gather, first comes the shooting priority in the ranged phase: mounted archers first, then longbows, then crossbows, then shortbows. The arrows are likely to have different damages.
Then it comes the melee phase, in which cavalry hit first. Every weapon seems to have attack and defense values, so your longbows are more likely to survive combat than shortbows (either they have higher defense, or they are less likely to be targeted).
Horses tend to kick ass, but they are quite expensive to make, as they take lots of food.