Speaking of flavor, there was a book I discovered a while back called 'A Knight's Own Book of Chivalry'. It's a translated treatise by a French knight from the Hundred Years' War named Geoffroi de Charny, who died in the Battle of Poitiers where he had the honor of carrying the Oriflamme. It's a very good resource, as it was commissioned by the King of France to serve as a manual for a new order of French knights that the King had hoped to create.

As far as I know, it's the only book of chivalry written by an actual medieval knight. I highly recommend it.