For most investigators, this weakness is very punishing, especially those with low sanity, like most guardians.

However enter the dreamteam, Carolyn Fern and Peter Sylvestre! She complains how she'd like to eat something human or monstrous... dealing him 1 horror. He disbelieves it, heals his horror and pays her for her great jokes. If this isn't a win-win situation, turning this weakness into a great source of income?

Building around these cards, Calling in Favors allows you to search for peter but requires you to have 4-6 allies in total to work consistently. Those cheap seeker soaks work pretty well.

To get the weakness into play isn't as easy, but any seeker card, draw or tutor helps to locate it. As weakness, you don't even need to spend an action to play it.

The accompanying Monstrous Transformation isn't as beneficial for her, as it reduces her to 2. But it boosts her to 5, so she can fight for once. However it's not very likely you'll see this card every game with only 1 copy in your deck and your focus on finding the weakness, so i wouldn't rely on it.