Have you ever had a favorite sword, or really important item (say, some enchanted gloves or Dark Brotherhood gear) and you accidentally sold it, or dropped it down a drain? Or a draugr shouted a disarm shout at you and your favorite sword went flying across the room, never to be found again? Do you wish that the game would have checked with you first?
Keepsakes: Item Protection will allow you to mark items as "keepsakes", and will show confirmation menus before you sell or drop these items - or, if the item is about to be disarmed. You can set any item as a keepsake except for consumables (potions and food), and gold. It works for modded items too! The mod is fully configurable, so you can change the hotkeys to mark an item as a keepsake or check if it's a keepsake; whether dropping/moving of a keepsake is allowed; whether selling of the keepsake is allowed; whether disarming of keepsakes is allowed; whether dropping/moving or selling an item will remove the keepsake flag on that type of item; and an option to clear all keepsakes of their flag.
To mark/unmark an item as a keepsake, just hover over it in your inventory and press the hotkey. You can do the same thing but with a different hotkey to check the keepsake status of an item.