dabster vs past master

dabster

noun
  • An expert; one who is master of their profession. 

  • A handy person. 

  • A dabbler or bungler. 

past master

noun
  • One who has an extremely high level of ability or knowledge within an area of achievement or expertise. 

  • Someone who has previously been a master at a given lodge. 

How often have the words dabster and past master occurred in a corpus of books? (source: Google Ngram Viewer )