As Eli pointed out, previous one is NG. How about something like this to call emacsclientw?
set EMACS_DIR=C:\emacs-26.1 set EMACSCLIENT=%EMACS_DIR%\bin\emacsclientw set ALTERNATE_EDITOR=%EMACS_DIR%\bin\runemacs assoc .vhd=vhdfile ftype vhdfile="%EMACSCLIENT%" --create-frame --no-wait --alternate-editor "%ALTERNATE_EDITOR%" "%%1"
