Extra Loot ? Edit
I've just discovered something. It may well apply to the other 2 quests also. Not have enough space in you inventory to uncover the last tomb, in my case I could only grab two out of the four items, and one can not get the spirit protection yet. Rush off to a merchant to sell what you have and then return; for sure the foe has respawned, but when you get to open the tomb again it has all 4 items there once more. Unsure, by that stage of the game, it is that exciting, but it's there as a wealth generator if required.