There's apparently a few shaders scattered throughout the game the require certain challenges to be met. This is the only one I know of though. However Ai Vinyl might be right as when I went to source a link all the ones I looked at have had the objective of 1000 precision kills in the crucible scrubbed. There are however a few arguments raging across the web if you google the Superblack shader with people who've broken the 1000kills and yet to get it