And you need to do this with a very limited amount of equipment slots and without bogging your characters down with too much heavy gear, so you will have to compromise at some point. While regular troops can afford the luxury to specialize on some roles, your characters waste much of their potential if they don't contribute to all of them. This is less vital for companions, but the main character will need a ranged weapon, if only to deal with those pesky horse archers you can't catch and enemies stuck in inaccessible places during a siege. On top of that, players need to protect themselves from melee and ranged attacks, and should have some way to fight on both distances as well.
They will face infantry and cavalry on open terrain, fight in mountains to the detriment of cavalry, and get stuck in close quarters combat during sieges.
