Just a warning, do NOT put a key of light/shadow into an Arcane Chest you find in the Shimmer underground area. It will somehow turn every furniture block invisible, make the Arcane Chest disappear, and you will not be able to fix it without reverting to a backup save. If you've done this accidentally, just Alt + F4. Might have something to do with the fact that it's the only chest to take up double the space?