Various shaders are bugged with the introduction of DX11, and some bugged prior to that. Example being that some infantry weapons and cosmetics use the vehicle shader, these weapons don't play nicely with the cloak shader. Currently, the same is going for the shield shader when it's applied to some of your weapons.
At any rate, the bug is in the process of being fixed (both the shield and cloak shaders have tasks in for them.)
I do agree in general though. If we had more shader options, and more flexible options for screen effects, we could message a lot of the first person effects better.