The obvious choice for this conversion would be to use the original software for .mwd documents - Mariner Write. However, it is only available for OS X, so if you do not have access to a Mac computer, you ma have trouble working with this document. It seems the LibreOffice Write supposedly supports at least some version of .mwd documents, so it's worth a shot.
Found 2 different conversion types using the same filename extensions.
Conversion mwd to doc type 1:
Convert from Mariner Write document file to Microsoft Word document (prior version 2007).
Multiplatform software - convert mwd to doc on any platform
LibreOffice Write is a complete word processor and document publishing tool that supports a plethora of document formats and has many innovative features. It's an open source software that comes as an integral part of LibreOffice suite.
File type (from-> to)
Convert from mwd file
Mariner Write document file
to doc file
Microsoft Word document (prior version 2007)
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned mwd to doc. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Conversion mwd to doc type 2:
Convert from Mariner Write document file to Document file.
Apple macOS / Mac OS X software - convert mwd to doc on OS X
Mariner Write is a dedicated document and word processing software for Mac OS X. Write has all the functions one would expect from a modern word processor and is useful for both casual and professional computer users.