During the early feudal period, fealty was not anything like absolute subservience, and was actually somewhat democratic (at least among nobles), to the point where "for a lord to marry, he required the assent of all of his vassals to the marriage." Not the sort of stuff we usually see in modern portrayals of feudalism, but eminently suitable to ACKS domain play.
Tournaments began as basically 'small-scale wars' at a mutually agreeable time and place, with the defeated usually being taken prisoner and ransomed. They were a source of income as well as a way to alleviate boredom in peaceful times. Using peasant footsoldiers was uncommon, but occasionally done. Only later did these tournaments evolve into jousts and more ordered forms of martial competition.
There existed three main strains of chivalry, which evolved over time and were often in conflict:
- Martial chivalry - Loyalty, bravery, skill at arms, and ambition. Those traits which made a fighter effective. The earliest form of chivalry.
- Ecclesiastical chivalry - Piety, humility, charity, and service to the church. Subverted martial ambition to "the search for glory in the name of God" by permitting martial glory to earn admission to Heaven, opposed tournaments as vainglorious and wars between Christians as destructive to Christendom.
- Courtly chivalry - Wit, skill in music and poetry, love and the willingness to suffer any indignity in the name of one's distant maiden in a tower. Broadly opposed by proponents of ecclesiastical chivalry due to its tendency to lead to adultery, while some proponents of martial chivalry found it distasteful to have to woo women gently.
But if I were to run a medievalist game... I think a proper 'knight' class would best be split into several tracks along the lines above. Would add a nice bit of period philosophical conflict to the mix, and provide for some variation among 'ye olde fighting men'. Working within ACKS' class-building system, I could definitely see Knight Errant being Fighting 2 HD 2, Brother Militant being Fighting 2 HD 1 Divine 1, and Courtier being something like Fighting 2 HD 1 Thief 1 with skills or power-swaps focused on interaction.
In any case, it was a worthwhile and enjoyable read, and small enough that I may keep it around for later reference.