clincher vs coup de grâce

clincher

noun
  • That which clinches; that which makes something final or firm. 

  • A tyre with a bead around the edge to attach to the rim of the wheel when inflated. 

coup de grâce

noun
  • A final blow or shot given to kill a wounded person or animal. 

  • A remarkable finishing action. 

How often have the words clincher and coup de grâce occurred in a corpus of books? (source: Google Ngram Viewer )