Claim: The word "henchman" has appeared in the name of Hengest (Hengist and Horsa; legendary brothers said to have led the Angles, Saxons and Jutes in their invasion of Britain in the 5th century), the Saxon chieftain, which was often rendered as Henxman in medieval English, then the word became obsolete for grooms in English from the middle of the 18th century, but was retained in Scots as "personal attendant of a Highland chief".
Evidence: The word became obsolete for grooms in English from the middle of the 17th century, but was retained in Scots as "personal attendant of a Highland chief".