Fixing broken smoothing groups for WoW models in 3DSMax
This is very outdated knowledge and should generally not be used. It can cause weighting issues, and you should generally fix the normals via the edit normals modifier.
After opening a WoW model in 3DS Max that you exported from WoW Model Viewer, you might have noticed that it's not smooth like in WoW. In order to fix this, you have to recalculate the smoothing groups.
Select your model in the viewport and click on the "Modify" tab located in the right panel. Click on Turbosmooth and remove it, as it breaks the rig. If you want to use Turbosmooth, see Applying Turbosmooth on already rigged mesh. Create a new Modifier "Edit mesh" below the Skin modifier, and hide the whole head (including eyes, face and hair) and the hanging part of the tabard. This step is important, because if it's skipped, it will create artifacts on the face.
Forcing recalculation of smoothing groups
Create a new "Edit mesh" on top of the last "Edit mesh" layer we used to hide the head and tabard. Now select all vertexes on the model (Selection -> Vertex) and under the "Edit Geometry" menu, press on the "Break" button. After that, go to "Weld" and weld the selected model with the force of 0.01 (Weld -> Selected). After that, you should have more smoother model now.