by-blow vs longsword

by-blow

noun
  • A blow struck to the side or from the side, as in swordplay; a secondary or incidental strike of any sort. 

  • An illegitimate child; a child of an unknown or unmarried father. 

longsword

noun
  • A European sword with a long, straight double-edged blade, a cruciform hilt, and a grip for two-handed use; prevalent from the 14th to 16th centuries. 

  • Any type of sword that is comparatively long; depending on context, applied to swords of the Bronze Age, Migration period, Viking Age and Renaissance era. 

How often have the words by-blow and longsword occurred in a corpus of books? (source: Google Ngram Viewer )