disengage vs unpen

disengage

verb
  • To release or loosen from something that binds, entangles, holds, or interlocks. 

noun
  • A circular movement of the blade that avoids the opponent's parry 

unpen

verb
  • To release from a pen. 

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