will

n. a legal document declaring a person's wishes regarding the disposal of their property when they die — see also estate, probate
  Ferdinand Bloch-Bauer died in Switzerland shortly after the war, in extreme poverty, never having retrieved his property, which he left to Maria Altmann and her brother and sister in his will.

will v. leave or give by will after one's death

We usually say "My aunt left me her diamond necklace in her will" rather than "My aunt willed me her diamond necklace."

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witness

n. someone who comes to court and tells what he knows about a matter before the court — see testify

  Every day, in courtrooms across the country, economists, statisticians, engineers, doctors, and psychologists raise their right hand and swear to tell the truth.

  Expert witnesses are used in all types of cases.
v. to perceive an event by seeing, hearing, smelling or other sensory perception

  He witnessed the accident on his way home.

The verb for what a witness does in a courtroom is testify.