Green’s Dictionary of Slang

one who hits, e.g. a boxer.

1890		Nat. Police Gaz. (NY) 3 May 6/2: Byrne’s Brawny Biffers were also doing the charity act with Boston's Nationals. The City of Churches made nine runs in the first three innings, and then felt ashamed of themselves for being so greedy.
1893		Bird o’ Freedom (Sydney) 30 Sept. 5/2: I’m a biffer / Not a bluffer / And I differ / From a duffer.
1908		Sun (Kalgoorlie, WA) 6 Sept. 4/8: Now, we haven’t a bruiser or biffer / I’d back to play up to the Yank.
1910		Sun. Times (Perth) 27 Mar. 2nd sect. 11/3: A local biffer who had ideas one time of tackling Tommy Burns for the heavyweight championship of the world.
1996		J. Byrell Lairs, Urgers & Coat-Tuggers 155: As he tries to sidestep the trio of blotto biffers, a big black paddywagon skids into the kerb.
1996		J. Byrell Lairs, Urgers & Coat-Tuggers 51: There was the Adams Quintet, Charlie Boy and his two biffer-boys, a slick local dip and [...] two sheilas.
2009		T. Black Gutted 51: One of the beer guts stood in front of me [...] He was a big biffer.
2013		T. Black Ringer [ebook] A big beefy biffer in black leather [...] a stack of wee star tats to complete the look.