Ok i will explain you.
The skin files defines somes 3D params, like vertices and triangles.
Triangles are 3 vertices who defines the texture on the model.
IT's coded in 2 bytes, or 65535 in hexadecimal.
Warlord of Dreanor HD models have more than 65535 triangles, so the values can't be entered in the skin files.
Blizzard use a system who read the 01 after the id in the submeshes.
The last submeshes, which StartTriangles > 65535 are fucked up
Ears, Legs are last submeshes :/
For the feets, in WoD, Models have 2 differents feets, so this is a new submesh ID (20) who didn't exist in mop or cataclysm, Wowmodelviewer don't show it, but ingame you can see it.
I hope your understand me, there is not really a good solution, i have to delete some submeshes to reach the 65535 limits.