fight vs take on

fight

verb
  • To engage in combat with; to oppose physically, to contest with. 

  • To conduct or engage in (battle, warfare etc.). 

  • Of colours or other design elements: to clash; to fail to harmonize. 

  • To try to overpower; to fiercely counteract. 

  • To contend in physical conflict, either singly or in war, battle etc. 

  • To contend in physical conflict with each other, either singly or in war, battle etc. 

  • To strive for something; to campaign or contend for success. 

noun
  • An occasion of fighting. 

  • A physical confrontation or combat between two or more people or groups. 

  • A conflict, possibly nonphysical, with opposing ideas or forces; strife. 

  • The will or ability to fight. 

  • A boxing or martial arts match. 

take on

verb
  • To attempt to fight, compete with, or engage with. 

  • To assume or take responsibility for. 

  • To (attempt to) dribble round (an opposition player). 

  • To catch on, do well; to become popular. 

  • To obtain the services of (a person) in exchange for remuneration; to give someone a job. 

  • To begin to have or exhibit. 

  • To acquire, bring in, or introduce. 

  • To grieve or be concerned (about something or someone). 

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