averment vs credentials

averment

noun
  • verification; establishment by evidence. 

  • The act of averring, or that which is averred; positive assertion. 

  • A positive statement of facts; an allegation; an offer to justify or prove what is alleged. 

credentials

noun
  • Documentary evidence of someone's right to credit or authority, especially such a document given to an ambassador by a country. 

  • login data 

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