On medieval Titles.

[OldeEnglish40]

I wrote this in the history form on my ancestor but felt it might be more appropriate here. There is a charter to a Robert Vaus in 1451 from william 8th earl of douglas Robert is reffered to as "Dilecto Armigero Suo" our beloved Esquire bieng that he was older by a few years and that this was barely two years after the battle of Sark, and other sources saying we was "Esquired" to him. Would this mean that he was just Esquire, a knight landless or without vows, Or would, bieng William was Earl Douglas, be using this as address to his supporter like how a baron or knight etc. would be esquired to a king, though not technically Esquires?