armor-plated vs protected

armor-plated

adj
  • Covered with a hard steel plate; especially of vehicles, boats, and defenses. 

protected

adj
  • defended 

  • Having the protected access modifier, indicating that a program element is accessible to subclasses but not to the program in general. 

How often have the words armor-plated and protected occurred in a corpus of books? (source: Google Ngram Viewer )