fealty vs piety

fealty

noun
  • Fidelity to one's lord or master; the feudal obligation by which the tenant or vassal was bound to be faithful to his lord. 

  • The oath by which this obligation was assumed. 

piety

noun
  • Reverence and devotion to God. 

  • A devout act or thought. 

  • A belief that is accepted unthinkingly and with undue reverence. 

  • Similar reverence to one's parents and family or to one's country. 

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