liability vs saving grace

liability

noun
  • A handicap that holds something back, a drawback, someone or something that is a burden to whoever is required to take care of them; an individual or action that exposes others to greater risk. 

  • Any item recorded on the right-hand side of a balance sheet. 

  • The condition of being susceptible to something. 

  • An obligation, debt or responsibility owed to someone. 

  • A person on a team that is more of a hindrance than a help. 

  • The likelihood of something happening. 

saving grace

noun
  • A redeeming quality or factor. 

  • God's grace or blessing, enabling sinners to attain salvation. 

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