i like it but i'm going for a +3 catch
Okay, let's review:
* If your abilities only protect you against something specific, you get a +2 discount. If they protect you against everything except something specific, you get nothing.
* If the Catch is bypassed by something that anyone could reasonably get access to, but usually doesn’t carry on them (like cold iron), you get a +2. If it is bypassed by something only a rare class of people in the world have (like True Magic), you get a +1. If it is bypassed by something only one or two people in the world have access to or could produce (like a Sword of the Cross), you get nothing. Even the mere presence of the thing that satisfies your Catch will cause you discomfort (and may be grounds for a compel or something similar).
* If almost anyone with an awareness of the supernatural knows about the Catch or could easily find out (like from the Paranet, or Bram Stoker’s Dracula if you’re a Black Court vampire), you get a +2. If knowledge of the Catch requires access to specific research material that could be restricted (like a wizard’s library), you get a +1. If knowledge of the Catch requires knowing you personally to learn about it (like the effect of Judas’ Noose on Nicodemus), you get nothing.
I'm betting you want to be protected against everything except something specific, so zero for that.
To get a +3, we're looking for something bypassed by a rare thing for +1 but which anyone could easily find out about for +2; or something which is reasonably common for +2 but requires research to learn about.
Which of those two are you angling for?