One of the "take a bunch of damage and.or horror" signature weaknesses, unusual for being randomized. Looking at the two elements, the effect and the discard condition, we get:

The effect: You take 0-4 damage and horror, which is unlikely to kill Jim, but it's unpleasant, as it can lose a scenario or campaign and/or net you a Trauma if you are unlucky. The 3 campaigns that make Jim more powerful makes this more deadly, which is a nice balance. Olive McBride can mitigate it (or make it worse), and Dark Prophecy can help. Sadly, Eldritch Inspiration is no help at all. I guess Jacqueline could help out, but what is the chance of Jim and her being in the same scenario?

The discard condition: You draw it, it's Revelation effect happens, you discard it. Simple, but it can happen multiple times, if you deck yourself or play Quantum Flux.

All in all, this is an average signature weakness, maybe a bit above in some campaigns/scenarios.