deharden vs enervate

deharden

verb
  • To make or become less hard (resistant to pressure). 

enervate

verb
  • To reduce strength or energy; debilitate. 

  • To weaken morally or mentally. 

  • To partially or completely remove a nerve. 

adj
  • Made feeble; weakened. 

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