A nobleman doesn't fight. He stands in the back row and "supervises". Occasionally a plucky enemy infantryman makes it to him, and gets put down by nobleman's superior swordsmanship skills. (Even 5% is pretty good odds against a peasant.) Then the nobleman complains that he got peasant blood on his plate-mail.
You allow peasants to take the battlefield? You have dishonoured the fallen. I ensure that only minor nobility make up my units, and will simply not engage peasants upon the field of honour.
