alighten vs buff up

alighten

verb
  • To make light; to illuminate or brighten. 

  • To lighten; to reduce in weight or heaviness. 

  • To alight, to dismount or get down from. 

  • To alight; to land, to descend and rest. 

buff up

verb
  • To shine; to make shiny. 

  • To improve. 

  • To become more muscular. 

  • To study hard to learn a particular subject. 

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