I doubt that reblessing a Win32::OLE object will work as you intend it to, because Win32::OLE objects live mainly in C/XS space. I recommend you aggregate the WMI object instead of trying to extend it, and delegate all unknown methods to the WMI object via AUTOLOAD:

sub AUTOLOAD {
    my $self = shift;
    (my $meth = $AUTOLOAD) =~ s/.*::/;

    # Now call the method on the WMI object
    $self->{wmi}->$meth(@_);
}
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The above method could be refined further to play with the stack so that all error messages point to the real caller instead of the reflection method, but for a first stab, this approach is OK.