Mary, The info came from the 19th Century Bermuda wills compiled by Hallett into book form. The introduction reads:
researchers are encouraged to apply to the Bermuda Archives, Government Administration Building, 30 Parliament Street, Hamilton, HM-12, Bermuda, for photocopies of documents of interest to them, using the reference numbers as given in this index.
So simply write to them quoting the name Robert STEED and the number of the will: W21:135 and the two dates.
If you include your email address they can contact you and give you the cost of mailing the info to you.