AElflaed note: This was lifted from Cathyn's website so I could edit and preserve it. It might still be out there elsewhere as well.
Prowess is the least of the Knightly Virtues in my mind. Look at the physical specimens you see on the battlefield, and recognize that genetics are an element of prowess. Look at any college football game, and you'll see talented players demonstrating their considerable prowess on their chosen battlefield, players who will be judged to not have enough prowess to advance to the professional level. Anyone can be born strong, anyone can be born weak. Some great deal of credit needs be extended to those who take their limited physical gifts and develop prowess in spite of not being 6'4" and 250lbs of lean muscle mass. However, prowess is still nothing more than physical skill. In our Society, this skill translates to winning swordfights. Prowess without Chivalry is cheating, Prowess without Honor is murder, Prowess without Modesty is braggadocio. Prowess without the other virtues is no virtue at all.
A Knight must be prepared to answer his King's call upon the field of war, and his Prowess serves in this purpose, but even the mightiest Knight might find himself dragged down by twenty peseants. Do not undervalue Prowess, but don't overvalue it, either.