User-friendly Word-type Editor for XML

I have an XML file that stores many business letters (in Report tags). The end user needs a user-friendly editor (MS Word or something like it) that will allow them to open these letters and edit them easily. They cannot see the XML tags or have the ability to modify the tags- they just need to be able to edit the contents (verbiage) and formatting of the letters. There is currently no XSL file so you may need to build that to allow for use in an editor. Willing to purchase a 3rd party editor (based on your recommendations) and just have you create the XSL file and/or adjust the XML file as needed to work with purchased editor. Ideally would like to get this to work with MS Word. This XML file is currently linked to custom software application that customizes these letters - any changes to the XML file will need to still work with the custom app. Please see attached sample XML file containing one letter.