Looks like a desaturated, scaled and darkened texture to me. Is that all it is? What does it do? I think I need to make them for my armor since the vanilla armor I'm skinning has them.

Specular map?

Wouldn't that be _s? I've found a little more info and it appears the general consensus is that it's an environment map, but I haven't found anything definitive on how to make one.

OK, found a little more info, so I exported all my diffuse textures as .png files, pulled them up in GIMP, scaled them, desaturated them and used the brightness>curves to darken them up a bit. Then I exported as DTX1 with mipmaps because that's what a thread I found said to export as. I then put those textures in the first Environment Map slot of my texture set, and it definitely toned down the shine/reflection, and I'm not crashing or seeing any strange behavior. I compared it to the regular Steel Plate in the sun and they are almost identical in terms of shine, with the difference being my new retextured version of course.

So can I fairly safely assume that what I have done is correct, or have I missed anything?