The games' handling of stolen items is a bit primitive, so it doesn't surprise me Hrnchamd feels there is nothing that can be done to help here.
Well, I wouldn't say it's not a problem. I was just bringing it up again because I had another idea. *shrugs*
Anyway, great work so far guys! I think what makes this brilliant is the way all of the modifications are optional. Thank you for making it that way

As suggested, you could use MGE. Another option is batch conversion in an image editing program.
@Hrnchamd: Speaking of the elemental barriers, they do affect arrows. I know some people don't like it, so I'm suggesting it. It would be pretty nice if the NPC health bar could show when they take damage from them as well.