grappling iron vs safeguard

grappling iron

noun
  • A metal hook, attached to the end of a line, used to hold two ships together. 

safeguard

verb
  • To escort safely. 

  • To implement safeguarding. 

  • To protect, to keep safe. 

noun
  • A safe-conduct or passport, especially in time of war. 

  • Something that serves as a guard or protection; a defense. 

  • One who, or that which, defends or protects; defence; protection. 

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