degrade vs weaken

degrade

verb
  • To lower in value or social position. 

  • To reduce in altitude or magnitude, as hills and mountains; to wear down. 

  • To reduce in quality or purity. 

weaken

verb
  • To become weaker or less strong. 

  • To make weaker or less strong. 

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