ballsiness vs mettle

ballsiness

noun
  • The condition of being ballsy; courage. 

mettle

noun
  • A quality of endurance and courage. 

  • Good temperament and character. 

adj
  • Spirited, vigorous, stout-hearted. 

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