Blessed
From Ultima Online Forever Wiki
Blessed items cannot be looted by other players and return to your pack when you are resurrected. Individual items can be blessed or containers, pouches, and bags can be blessed.
Be careful to not put blessed items into a non-blessed container/bags as the non-blessed/bags container can be looted by others. Rule of thumb: keep all blessed items in your MAIN BACKPACK at all times.
You can know if an item, container, or bag is blessed by hovering an item and the word "Blessed" will appear below the name.