This question is out of curiosity more than anything:

When I met with Vivec, at some point during the dialog (When given Wraithguard, I think) I saw the phrase "Unique Dwemer Artifact removed from your inventory.

Now, I know the artifact in question is the version of wraithguard that you get if you kill Vivec, but I never noticed it being added to my inventory.

So what gives, do the scripts add both and take away the Unique one. I did save the game and kill Vivec to check...he didn't have it... (Tough old coot....took two tries.)

It may have been something that MCP or some of the other "standard unofficial patches" might have changed...

According to the construction set there's a trigger when Vivec says

that removes the "unique dwemer artifact" from your inventory. However, looking at Vivec's dialog there is no point where the artifact is added to your inventory in the first place, and the only way that particular command would trigger is if you had it in your inventory. I don't think you can get it without killing Vivec, so it would seem to me as though this particular dialog entry would be unreachable (though there are several identical entries with the same text without the command to remove the artifact from your inventory). So... beats me why you saw that message