tip one's hand vs unveil

tip one's hand

verb
  • To inadvertently reveal any secret, particularly a secret that puts one at an advantage or disadvantage. 

  • In card playing, to accidentally reveal one's cards or hand. 

unveil

verb
  • To remove a veil from; to uncover; to reveal something hidden. 

  • To remove a veil; to reveal oneself. 

  • to show, especially for the first time 

How often have the words tip one's hand and unveil occurred in a corpus of books? (source: Google Ngram Viewer )