Villeins would probably have been armed by the lord. Remember serfs weren't allowed to move or even marry without the consent of their Lord. Therefore the lord would keep the weapons in the castle and then dole them out when he called on them to fight. Only the knights were trained professional fighters who were properly armed and armoured. It's why a few knights in a castle could control vast areas of England. They were the mechanised infantry of the era. Read the 1152 Assizes and you see laws like. You cannot export arms and that no lord may have more arms than he is legally entitled to. The Bear.