Since the Dark Master's plot was revealed to me, I have attempted to learn more of this weapon he holds so dear. According to historical records, the Mortuum Vivicus was a gift from our Lord and Master to the unworthy king of a long-forgotten city.
Those unworthy servants stood on the verge of greatness! To their great loss and eternal shame, the fools were unable to accomplish the simple tasks our Master set before them, and he withdrew the Vivicus from Tamriel. It was lost to the Faithful.
If the Master's plan comes to fruition—if enough souls can be gathered to his side—the servants of the Lord of Lies would be more powerful than any mere king or queen. Truly, Tamriel would burn in the Master's fire!