mastery vs unskill

mastery

noun
  • Superiority in war or competition; victory; triumph; preeminence. 

  • The position or authority of a master; dominion; command; supremacy; superiority. 

  • The act or process of mastering; the state of having mastered; expertise. 

unskill

noun
  • Foolish conduct; wrongdoing. 

  • Lack of skill; skilllessness. 

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