Extract it from Media.pk2 with PK2 Extractor.
The file is a TXT so you can open it with NotePad or WordPad.
But the truth is that you don't need to use this method to edit. Glows can be made in Media.pk2 directly with a Hex editor. XVI32 is very useful and easy to use.
Here:
http://www.silkroadforums.com/viewtopic.php?t=39714
I couldn't make it work until Crumpets posted this, now it works hehe