guardian angel vs preserver

guardian angel

noun
  • A person who watches over another. 

  • A tutelary angel watching over a particular person in monotheistic contexts. 

preserver

noun
  • A person who prepares preserves of fruit or preserved meats. 

  • A person who refinishes furniture. 

  • One who preserves. 

  • A life preserver. 

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