One of those things I thought I'd posted, but apparently had not.
As I've talked about before, I like the system of martial arts laid out in AD&D's Oriental Adventures; it fits well in the system, and allows warriors, even those with the same equipment, to be very different, and pick up some special abilities to make them stand out from the hoi polloi.
And, so, I worked out a way to use them in Castles and Crusades.
And here it is.
Briefly, you receive the basics of a martial arts style at your first +1 BtH, and a maneuver from it at every even BAB. Monks, despite starting at +0 BtH, get a style at 1st level, and get their first maneuver at 3rd level, and then follow on the same upgrade schedule as everyone else (at +4, 6, 8, etc. of BtH).
Unlike AD&D, Castles and Crusades does not (by default) have a fungible character advancement resource like AD&D's proficiency slots. Thus, this is presented as a bonus, not just an option. Obviously, if the CK is using styles in their game, it is best to use them for everyone... the wizard will never get GOOD at the martial arts, but by the time they finally get a +1 BAB, I would guess they've been in enough fights that they have some semblance of their own style. However, if you want to limit the classes that have access to it, I would include both the rogue and assassin, in addition to the likely Barbarian, Bard, Fighter, Knight, Monk, Paladin, and Ranger mix you are likely thinking of; rogues and assassins don't need to get left yet further behind.
