Originally Posted by
Grymskvll
In DBC, you'd need to edit the original model's size numbers but I'm not sure if that's possible with playable races.
What I'd do is get Glitchy's Model Edit Suite (can be found stickied in the guides and apps section), convert the Illidan.m2 to .obj (use the model injector), then open the illidan.obj in any 3D editing application such as 3DS Max and just scale the entire model down.
If you don't want to go through the trouble of downloading and installing a 3D editing application, you could upload it here and ask someone to do it (I'll do it if I don't forget).
After that, save the .obj again and convert back to .m2 with Glitchy's injector.