Yoked Virindi tells you, "Yes, I still obey the Master. Please. If you have the Glowing Virindi Cloak, I will take it in exchange for the Two Handed Singularity Sword. Please. If you have a Two Handed Singularity Sword, let me enhance it for you. Please?"
You give Yoked Virindi Glowing Mosswart Shroud.
Yoked Virindi gives you Singularity Greatsword.