The Collaborative International Dictionary of English v.0.48:

Embraceor \Em*brace"or\, n. (Law)
   One guilty of embracery.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

EMBRACEOR, criminal law. He who, when a matter is on trial between party and
party, comes to the bar with one of the parties, and having received some
reward so to do, speaks in the case or privily labors the jury, or stands
there to survey or overlook them, thereby to put them in fear and doubt of
the matter. But persons learned in the law may speak in a case for their
clients. Co. Litt. 369; Terms de la Ley. A person who is guilty of
embracery. (q.v.)