Swapping Robe Textures

[Nolvak]

While trying to swap out the textures for the heirloom cloth robe (Tattered Dreadmist Robe) to that of a robe in heroic Magisters' Terrace (Scarlet Sin'dorei Robes), I came upon the problem of the Sin'dorei Robes having textures that the Dreadmist Robe did not. I attempted to edit the ItemDisplayInfo.dbc in order to make it look for the extra texture (Sleeve - ArmLower), however the texture now appears as though it's wrapped tightly around the lower arm rather than "puffed out" and loose like the normal item's appearance. Considering the lower arm texture of the new robe is at least making it onto the lower arm, I consider this progress, however I've been teaching myself as I go along as I've never had to do something like this before. If it were the case of extra textures on the robe I'm replacing, it would be as simple as replacing them with blanks, but to my dispair, I've no such luck as to have that problem.

I was just curious as to what I could do to remedy this situation, any help is much appreciated. Also, I apologize for not attaching links to wowhead for the two particular robes, my post count doesn't yet allow me to do so.