Tamed 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 Singularity Sword. Please. If you have a Singularity Sword, let me enhance it for you. Please?"
You give Tamed Virindi Glowing Mosswart Shroud.
Tamed Virindi gives you Singularity Sword.