If you're wanting to loot both display cases in the basement (after killing Adramahlikh), cast Blood Rain one of them, open the case, loot the items, clear the blood (Tornado is OP for this), then quicksave and reload to reset the second display case. Cast Blood Rain on the second display case, open it, and loot it. One thing I've noticed that's very important is to NOT CLOSE THE DISPLAY CASES. If you close them after looting them, the items that were inside cannot be equipped or right-clicked on, making them completely useless. The game seems to think they're in the case when you do that. Also, if you close the display cases and drop the items on the floor, you won't be able to pick them up again. In this way, you can equip all five artifacts from the chests.