Man-at-arms was a term used from the High Medieval to Renaissance periods to describe a soldier, almost always a professional warrior in the sense of being well-trained in the use of arms, who served as a fully armoured heavy cavalryman. It could refer toknights or noblemen, and to members of their retinues or to mercenaries in companies under captains. Such men could serve for pay or through a feudal obligation. The terms knight and man-at-arms are often used interchangeably, but while all knights equipped for war certainly were men-at-arms, not all men-at-arms were knights. - Wikipedia :D