deathblow vs quietus

deathblow

noun
  • A strike or blow that leads to death, especially a coup de grace. 

  • Something that prevents the completion, or ends the existence, of a project etc.; a fatal setback. 

quietus

noun
  • Death. 

  • Final settlement (e.g., of a debt). 

  • A stillness or pause; something that quiets or represses; removal from activity. 

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