Don't like it don't use it! No, wait... :blink:
I suppose with 2-handed fighting there must be a way to sheath both weapons and, in this case, if one of them is your shield, then it would be a good solution to put it on your back. I think I've seen it on one of the art pictures also, so I don't know why it shouldn't be in?
Not that I care all that much though, as I always play in 1st person.. But I suppose for the vane moments of camera swooping around my character it would be cool