There can be several dates affiliated with a will.
First the will was written and dated with witnesses.
Second a date will relate to when the will was taken into the court for letters of administration aka the date it was "proven" (after the person died).
Third a date can be given for when the clerk of the court has recorded it into the record books.
Most wills will NOT have a death date. Most death dates affiliated with wills are listed in the "Probate" file.