quarterstaff vs shillelagh

quarterstaff

noun
  • A wooden staff of an approximate length between 2 and 2.5 meters, sometimes tipped with iron, used as a weapon in rural England during the Early Modern period. 

  • Fighting or exercise with the quarterstaff. 

shillelagh

noun
  • A wooden (traditionally blackthorn (sloe) wood) club ending with a large knob. 

  • Any cudgel, whether or not of Irish origin. 

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