Stupid newbie question: Katana

[Covax]

I've got a question, I'm huntung through the FAQs, got editing tools and GMax but all this stuff is alien to me. Here's my situation:

 

I've got a mod that replaces Lukes and Kyles sabers with Katanas. Now the trick is I would like to have a different texture for Luke's than for Kyles.

 

What I would like to know is what program I'd have to use to edit the existing file to change the texture? Or would I have to uncomplie it to use in another porgram?

[Bell]

you can use photo shop or paint shop pro