This is a odd “glitch” (I hope) that happens rarely. I can clearly recall this happening three times during the entire course of my play in this game.
After transmuting a Exotic armor piece twice (I like to redo my armor a lot) it seems the item becomes un-salvageable. Below is a screen shot of me trying to salvage the piece of armor with a standard salvage kit (not master, just the normal 25 use one but with 250 uses instead).
Just to note: This armor was bought on this character. Worn on this character at the start. Then transmuted and worn on this character. Then Transmuted and worn again.
Edit: I have already salvaged the rest of the set which had been through the same process. It is just this piece that is encountering this problem.
I am wondering; Is there a way to fix this so I can salvage this armor?
Did it originate from the Lyssa temple karma vendor in Orr? You can’t salvage karma bought items (you might be able to if you transmuted the stats away to get the rune out, but I’m not sure and doubt it.)