I wonder why they persist in strapping the guige like that? Do you see, in the pic, lower left hand where the guige terminates above the lower arm strap? You'll always get a rub there...it should terminate lower, left of the down point. If you look at pics of Sir James' or Sir Nathan's shield projects, you'll see the guige lays diagonally over the back of the shield- when you put it on, it goes from the shoulder down to the opposite side hip, that's how it should lie.
Still, that is a nice shield- and you'll want to get another if you plan on fighting with it because you wouldn't want to smash up such a pretty shield. Even though that's what it really is for.
My guess is they strap it that way since they use the existing mount points for the arm straps and grip.
Here's a few quick pictures of my shield on with the guige, and of how the strap sits. I'm right handed:
http://james-anderson-iii.com/projects/pages/templar-shield/Since I'm right handed, I have it hang "offset" so that it's behind my left arm, but not my right. Sorry for the really bad pictures, had to take them of myself. Hopefully it's good enough to show that the guige strap shouldn't be on your arm at all. You can try adjusting it. Also, looking at the picture it looks like yours is strapped for the 'smooth' side of the leather outwards; mine is opposite of that, the rough side of the leather faces outwards, and the smooth part on the inside. I did that so it won't have a rougher surface to be rubbing against mail/surcoat/etc.
Hard to have too many shields.