The inobvious: It's an Ankh, a sign for immortality, so why this effect? Why because many many many encounter cards deal damage incremental to your failure! Rotting Remains, Grasping Hands, that kind of stuff, most scenarios have 1 or 2 effects like these, so even if you're not trying to change failure into success, the Ancient Ankh might very well be very useful, regardless of class, not to mention the flexible skill icons.
Aegis of the Harbinger
Health: –. Sanity: 3.
Uses (4 charges).
When an investigator at your location would fail a test by more than 1, spend 1 charge: That investigator fails by 1, instead (even if he or she automatically failed).
Guardians of the Abyss #56. Abyssal Tribute #2.
The card does not work with Lucky! since it just makes you fail by 1, but does not set your skill value to skill difficulty - 1. — ak45 · 68