Green’s Dictionary of Slang

a knife-wielder, one who stabs.

1951		Kerouac On the Road (The Orig. Scroll) (2007) 254: Bill [...] started showing us how to disarm a would-be shivver in a dark alley.
1957		Kerouac On The Road (1972) 146: Showing us how to disarm a would-be shivver in a dark alley.