fluency vs locution

fluency

noun
  • The quality of being fluent in a language; A person's command of a particular language. 

  • The quality of smoothness of flow. 

  • The quality of consistently applying skill correctly in the manner of one well-practiced at it, requiring little deliberate thought to perform without mistakes 

locution

noun
  • Style of discourse or usage, or any particular utterance in such style. 

  • A phrase or expression connected to an individual or a group of individuals through repeated usage. 

  • A supernatural revelation where a religious figure, statue or icon speaks, usually to a saint. 

  • The use of a word or phrase in an unusual or specialized way. 

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