Green’s Dictionary of Slang

1. (US) a very attractive woman.

1870

J.C. Duval Big-Foot 277: She was a ‘deadener,’ I tell you, and a regular ‘knee-weakener’ in the bargain.

2. (Aus.) a bully, one who prefers to settle arguments through violence.

1936

A. Russell Gone Nomad 56: He fought ‘Tiger’ Martin, a professional pugilist and the ‘camp deadener,’ over some affair.