@echo off
setlocal enableextensions enabledelayedexpansion
call:Concat cmd "this is a demo" " of concat functionality." " Hopefully it will work;" " but it doesn't when I pass an" " * asterisk" " character"
echo %cmd%

@goto:end
@goto:eof

set LF=^


::^ two empty lines are necessary !! ^
:Concat
::Concatenates a given list of strings without including their quotes
::1 - output variable
::2* - strings to concat
echo(#%*
set /a xx=0
set "Concat_tempFlag=0"
set "Concat_temp="
set tryl=%*
set tryl=%tryl:" "="!LF!"%
for %%A in ("%tryl%") do (
    set /a xx+=1
    echo !xx! - %%A
    if !Concat_tempFlag!==1 (
        set Concat_temp=!Concat_temp!%%~A
    ) else (
        set Concat_tempFlag=1
    )
)
set "%~1="%Concat_temp%""
@goto:eof

:End
echo(Bye
exit /b 0