Imagine that this is the engine that they made halo reach with, it just had modifications. It's had a good run but it came out in like 2009. Nee engine could be crazy good.

I can't prove it but I think that all the gear shaders are literally a library of gear that are prerendered, most of them procedurally which is why some gear, like raid gear, tend to look good no matter what, while others almost everything looks like it was just randomly slapped on.. Instead of applying a shader to a current wireframe like a texture, they actually swap out the weapon you're viewing with a weapon from the rendered library. They have mentioned several times that rendering small changes requires a ponderous amount of resources, time and effort. And it explains some other oddities as well. That seems ridiculous given that all they have to do is slap a new texture on the piece of gear but it is what I think is happening.