ETYMOLOGY
back formation from manqueller (a murderer), from man + queller (a person or thing who subdues someone or something)
EXAMPLE
“… At which wordes kyng Edward sayd nothyng, but with his hād thrust hym from hym (or as some say, stroke him with his gauntlet) whom incontinent, they that stode about, whiche were George duke of Clarence Rychard duke of Gloucester, Thomas Marques Dorset, and Williā lord Hastynges, sodaynly murthered, & pitiously manquelled. The bit ternesse of which murder, some of the actors, after in their latter dayes tested and assayed by the very rod of Iustice and punishment of God. …”
From: The vnion of the two Noble and Illustre Famelies of Lancastre [and] Yorke
By Edward Hall, 1548
Lexicophilia 