I was able to barter for the staff from Dietmar and then killed him and got my stuff back. @Fedayin are you trying to open it in the room you found it? There is an issue with picking up barrels, containers, etc and opening them away from where you picked them up. To solve this drop the item, pick it up, open it. Should work. Hope they fix this as I like to carry containers and such to hold my stuff and better manage my inventory.
