Green’s Dictionary of Slang

a punch, a blow.

1820		Carlisle Patriot 9 Dec. 2: The wistycastors of Josh. were so tremendous, he spoilt the gentility of the swell and milled him down.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue n.p.: wisty castors Heavy blows given by scientific pugilists, tending to take the fight out of each other.
1824		Annals of Sporting 1 Mar. 199: [He] returned upon Goldie with a wisty castor under the dexter listener.
1832		Egan Bk of Sports 202: Neal [...] now and then put in a whisty-castor, which rather changed the look of Sam’s frontispiece.
1834		‘Jack Downing’ Andrew Jackson 40: Captin Hammond gave him wisty castors on the hed.