This item drop by rare Gravediggar or Brigand. You can farm this through following bounties:
Act 1 - Cemetry of Forsaken - Digger O'Dell
Act 1 - Cemetry of Forsaken - Dataminer
Also look for following rare outside of the Defiled Crypt, when farming the above mentioned bounties.
Act 1 - Cemetry of Forsaken - Lucious the Depraved (Brigand)
Some example pictures below: