We have no method for decoding MW stored passwords unfortunately.
NirSoft however has a utility program for Outlook here https://www.nirsoft.net/utils/pst_password.html
Note from the page : After you run PstPassword, the main window displays the list of all PST files of the current logged on user (Under Documents and Settings\User Name\Local Settings\Application Data\Microsoft\Outlook)
If you want to recover a password of PST file that doesn't appear in the default list, you can press F7 and select the desired PST file, or simply drag the PST file from Explorer window into the main window of PstPassword.