irresolution vs mettle

irresolution

noun
  • Lack of resolution; lack of decision or purpose; vacillation. 

mettle

adj
  • Spirited, vigorous, stout-hearted. 

noun
  • Good temperament and character. 

  • A quality of endurance and courage. 

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