Theuth

Available

 * http://fusisoft.net/software/software-theuth-demo/

Author

 * Daniele Fusi

Description
Theuth is a Microsoft Word addin that allows you to type polytonic Greek and Latin with diacritics and "to convert text written with any arbitrarily-encoded Greek font into a standard Unicode font, or vice-versa". It is one of the few tools allowing conversion to and from Unicode.

Required Microsoft .NET Runtime 4.7.2, and so presumably works best (?only) on Windows 10.