sandbagger

noun2

1. •
   One who sandbags (misleads about their ability level in order to win bets); a hustler.

   • The poker sandbagger would, upon being dealt a fantastic hand, delay upping the ante in order to lull the other players into a false sense of security. — 2011
2. •
   (historical) A robber who sandbags (suddenly strikes, with a sandbag or other object, so as to stun) victims.

   • The Day-Globe, Waco, Texas, July 5th., 1893, writing on "The Conscienceless Juror," says: […] 'Red Farrel' a notorious sandbagger and robber was on trial in Judge Moise's Court. — 1896