Green’s Dictionary of Slang

roberdsmen n.

also robardsmen, robberdsmen, robbersmen, roberts men, robin’s men
[early 14C SE Roberdsmen, a type of marauding vagabond, who were outlawed under an act of 1331; Ribton-Turner, A History of Vagrants (1887), notes the coincident 15C Roberts men who followed one Hugh Roberts, a former soldier and one of the leaders, with the better known Jack Cade (a.k.a. Jack Mendall) of the Peasants’ Revolt; Roberts fled after the revolt and lived as an outlaw with one hundred other ‘rakehells and vagabonds’ until he was killed, as a follower of Edward IV, during the Wars of the Roses]

(UK Und.) ‘the third (old) rank of the canting crew n.’, outlaw thieves who act, according to B.E., like real-life Robin Hoods.

[UK]R. Holme Academy of Armory Ch. iii item 68b: Give me leave to give you the names (as in their Canting Language they call themselves) of all (or most of such) as follow the Vagabond Trade, according to their Regiments or Divisions, as [...] 3. Robardesmen.
[UK]B.E. Dict. Canting Crew n.p.: Roberds-men c. the third (old) Rank of the Canting Crew, mighty Thieves, like Robin-hood.
[UK]New Canting Dict. [as cit. c.1698].
[UK]Grose Classical Dict. of the Vulgar Tongue n.p.: Robert’s men. The third old rank of the canting crew, mighty thieves, like Robin Hood.
[UK]Lex. Balatronicum [as cit. 1785].
T.E. Tomlins Law Dict. 549: robbersmen, or robberdsmen were a sort of thieves mentioned in the statutes (5 Edw. 3, &c.)... of whom Coke says, that Robin Hood lived in the reign of King Richard I, on the borders of England and Scotland by robbery, burning of houses, rapine and spoil, &c., and that these robberdsmen took name from him [F&H].
[UK]Egan Grose’s Classical Dict. of the Vulgar Tongue.
[UK]Morn. Post 13 Aug. 3/5: Statutes made in the time of Edward the king’s grandfather, of Roberdsmen and Drawlatches ‘be firmly holden and kept,’ and [...] it should be henceforth be lawful for Justices to take up all such vagabonds’.
[US]Matsell Vocabulum 74: robin’s men From Robin Hood. Expert thieves; grand larceny men; bank-robbers, etc.
[UK]Derbyshire Courier 2 May 8/2: Hampson [...] says he looks ‘upon Robin Hood and his men as ideal personages, who instead of lending their particular name to thieves, have received it from the general term Roberdsmen.
[US]Dly Dispatch (Richmond, VA) 1 Nov. 3/3: ‘Robin’s men’ are expert thieves and bank robbers.