Golden chalice

The Golden chalice is a quest item used in the Buyers and Cellars quest. It's the first task you get from the Thieves' Guild.

Buyers and Cellars
During Buyers and Cellars, it is revealed that it's currently located in the bank's vault. Though when talking to Chief Thief Robin he tells the player that a priest, being Father Urnhey, took it to his house.

When the player reaches Urnhey's house the player distracts him by lighting a fire under a window, and uses this distraction to steal the key and bring the chalice to Darren Lightfinger.