This has been updated to match my "Signature Weakness Project." I have done my best to make sure that the original content isn't altered too much, out of respect for any comments.
Another flavorful Signature Weakness from the Starter Decks. Looking at the two elements, the effect and the discard condition, we get:
The effect: It severely limits Jacqueline's special ability by making it impossible to cancel "bad stuff" tokens, effectively shutting it down until this can be cleared. It also shuts down Dark Prophecy, Defiance, Defiance (2), Grotesque Statue (2), Grotesque Statue (4), Olive McBride. It appears not to shut down Seal of the Elder Sign, Tides of Fate, Ward of Radiance, Voice of Ra. It would not affect either of the Will to Survives and probably other non-Mystic, non-Neutral cards, but Jacqueline can't take them, so let's not worry about that.
All things considered, this might be the worst of the Starter deck Signature Weaknesses. Nathaniel's just takes strategy and effort (or a whole turn of basic Fight), Harvey's could kill him at a bad moment, but it's one and done, Winifred's is more a roadbump than a Weakness, and Stella's, while a problem, can be cleared with . Jacqueline's Weakness could hang around for the entire game, although that's not all that likely, with 2-4 turns being average.