db2cmd is probably OK with utf8, the problem is that the Windows command prompt isn't. That's why you see the weird characters when you type the file.
So the command prompt is probably causing problems with db2cmd. According to what I just read (
here) the solution is to change the code page with the
chcp command and use a unicode compliant font (Lucida console is recommended).
I can't speak to this with great authority, since I use Linux most of the time. Take a look at the link and see what you think.