Well, lucky for you, I have been discussing this already a year ago. Take a look, I also made comparison pictures with other mistakes these developers did (which is especially true for the Lightforged Draenei).
They use a specific colorization for “Void”, namely the dark purple one you see in their heritage armor and in exactly two weapons. In WoD they also used the same gold color ID.
I can understand that, but you really should actually take your time and look at the items yourself. Seeing is believing, isn’t it.
They have been planned. Nobody wants to admit this, but unfortunately this “race” was something they cooked up very quickly. The truth lies perhaps somewhere between the lines. They have been working on both and needed to give the Artifact weapons also something what fits them race-wise (bows, you know, Alleria and so). But it’s also true that they have no access to Void Elf-based weapons and colorization at all. The heritage weapons have been not made available to them, which is another stupid decision by the developers.