decern vs fall on

decern

verb
  • See distinctly (with the eyes or the mind); distinguish (an object or fact); discern. 

  • transferred sense 

  • Decree a person etc. to be or to do something by judicial sentence.  (in the phrase “to decern in”, obsolete) To mulct in by decree of court. 

  • Decree by judicial sentence that something be done. 

  • intransitive 

  • with simple object 

fall on

verb
  • Of the eyes or gaze: to alight upon. 

  • To be assigned to; to acquire a new responsibility, duty or burden. 

  • To experience; to suffer; to fall upon. 

  • To occur on a particular day. 

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