who vs whosoever

who

pron
  • Whoever, he who, they who. 

  • With antecedent as subject. 

  • What person or people; which person or people; asks for the identity of someone; used in a direct or indirect question. 

  • With antecedent as object: whom. 

noun
  • A person under discussion; a question of which person. 

det
  • whose 

whosoever

pron
  • Whatever person or persons: emphasised or elaborated form of whoever. 

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