First of all, the following contents include those which might spoil your game, because of their power, usefulness or fatality to your game in wrong use. All I ask is that you agree to protect yourself, and agree not to complain even if your game should be broken. If you are not confident that you can use those without spoiling your game, I would strongly recommend you to ignore the following contents.
Much Effective Items
Some deadly/much effective items are hidden somewhere in Tamriel. Most of the items are hard to obtain. Diane sells a book "Legendary Items" which tells you the information on the items.
Miscellaneous Artifacts
Will grant you much advantage while they are in your inventory. They are sold by Mystina.
Extra Containers
When you meet Mystina's demand and give her what she has been looking for, she will provide a chest on a desk upstairs in Julienne's shop, where you can obtain ten keys and a note that tells you how to use the keys of the portable containers. You can open the container by accessing one in your inventory or through the hotkey. Regarding the use of the boxes, please see the following image by clicking it. Also, further information is described on a note which will be given with the keys by Mystina.
As the note mentions, "Key To Outer Space" is, so to speak, a portable trash can. The things placed into it will never come back again. Please be careful lest you regret.
Rusty Silver Shortsword
Lies in a sack near the I.C. Sewers. If the sword is in your inventory, someone might help you when you are dying...