Lens of Truth
The Lens of Truth is an artifact that lets you see the truth, obviously. It works the same as the Mask of Truth, found in Ocarina of Time. When peeked through, it lets you see what is actually there. Say there is a ladder, but it is invisible on a wall. If you look through the lens of truth then voila, the ladder will become visible. This item allows the truth to find its way to you, or vice versa. It also works in helping you see troublemaking spectre's from beyond the grave. As a side effect of its helpfulness, it costs magic power to use.
This item can be found in the bottom of the well as a child, but you first must drain the well water to get in.