The eye is an artifact, the remant of an extinct species. This resin preserved eye was once used as decoration for a dagger, and was used to enhance luck. Unfortunately for its owners, the eye was powerful and carried a mind of its own, and manipulated luck to its own ends. It guided its owner into the deep wilderness where they were killed.
If the eye and its owner's wills align, it can bring them great luck. Otherwise, it can bring great tragedy.