Untested :-)

for (map { $_->[1] } sort { $a->[0] <=> $b->[1] } map { [substr($_,6,2
+), $_] } @files) {
  print "fwlog" . $_ . ".Mar2005\n";
}
[download]

Update: I didn't notice that some of the lines had only one digit, and not two; hence, my solution with the substr will not work properly. Still, as you can see by the already three similar answers, this (the schwartzian transform) is the right way to go :-)