The top review of this card is 100% incorrect. The card works exactly as intended.
When you draw a basic weakness, it is considered to be an encounter card.
arkhamdb.com
- Weaknesses with an encounter cardtype (such as enemies or treacheries) are considered to be player cards while they are in their bearer’s deck, and are considered to be encounter cards while they are being resolved, and once they have entered play.
Encounter cards go to your threat area.
arkhamdb.com
- An investigator's threat area is a play area in which encounter cards currently engaged with and/or affecting an investigator are placed. The cards in an investigator's threat area are at the same location as the investigator.
So now it is in the same location as the investigator. Can we do anything with that? Yes, we can.
arkhamdb.com
- An investigator is permitted to activate abilities from the following sources: A scenario card that is in play and at the same location as the investigator. This includes the location itself, encounter cards placed at that location, and all encounter cards in the threat area of any investigator at that location.
Look above the word Narcolepsy and you'll see the word treachery.
So to recap:
Weaknesses with an encounter cardtype, such as treacheries, are considered encounter cards once they have entered play. Encounter cards go into an investigator's threat area. The threat area is considered to be at the same location as the investigator. Any investigator may use activate actions on encounter cards in the threat area of an investigator at their location.