arbalest vs atlatl

arbalest

noun
  • A crossbow. 

  • A crossbowman. 

atlatl

noun
  • A spearthrower consisting of a wooden stick with a thong or perpendicularly protruding hook on the rear end that grips a grove or socket on the butt of its accompanying spear (or dart), intended to steady the spear immediately prior to throwing, to increase its potential range when thrown, and to increase its force of penetration of the target. 

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