The Collaborative International Dictionary of English v.0.48:

Wag-halter \Wag"-hal`ter\, n. [Wag + halter.]
   One who moves or wears a halter; one likely to be hanged.
   [Colloq. & Obs.]
   [1913 Webster]

         I can tell you, I am a mad wag-halter.   --Marston.
   [1913 Webster]