The Collaborative International Dictionary of English v.0.48:

Dabster \Dab"ster\, n. [Cf. Dab an expert.]
   One who is skilled; a master of his business; a proficient;
   an adept. [Colloq.]
   [1913 Webster]

   Note: Sometimes improperly used for dabbler; as, "I am but a
         dabster with gentle art".
         [1913 Webster]