I think you can make an argument that it really is that rare.
Firstly, remember that not many people have access to true love. Lots of people could have access to it, but it's not something you can find on demand. Especially since looking for it probably makes it even harder to find (Since you're looking for it for profit, rather than out of love).
Secondly, weaponising it is bloody difficult. Remember that in a person it only works on vampires who choose to feed on them (Or whose vampire side is in control). You can be as truly loved as you want, but unless you have a token of that love, there's nothing you can do to force the catch on a vampire. Slap Lara all you want, she's not going to blister.
To actually weaponise it, you're going to need your true love to give you a weapon (or something you can improvise as a weapon) as a token of that love. Which, again, probably won't work if they're doing it so in order to trigger the catch - It probably needs to be given out of love, not with deliberately weaponising it as the goal. Otherwise it wouldn't be a "token of love". Even then, just being given something by the one you love isn't enough, or Whites would blister on contact with Harry's coat, which actually Thomas wears.
Thirdly, I seriously doubt it's well known outside of the WCV community (and I think it's reasonable to discount them for the purpose of calculating the catch's level of information - The fact that the vast, vast majority of people with knowledge to use the catch aren't capable of doing so really limits it's usefulness. Thomas is the only White seen to show love, and he's the black sheep of the family). Remember, Harry only finds out from Thomas, and I can't think of a single mention from the Council of that as their weakness. Harry never says "Don't worry, I'm protected" to Luccio, or Ebeneezer, when they're worried about Thomas preying on him. The WCV are masters of controlling information. It's basically their business (Just ask Stoker and the Blacks).
I agree.
I can however offer another perspective that helps support this.
I'm a cynic. That's what life does to you, or me in any case. I still consider myself a hopeless romantic. In many years i've never found anything close to what I'd consider the White Court catch. I think it is that rare.
Look at the divorce rate. How many people cheat?
People don't fall in love anymore they fall in lust. Then they fall out of lust and repeat the process. I applaud the few who actually understand the term love and enjoy it in life.
Point is...I know
hundreds of people, maybe
thousands peripherally. One couple had anything close to what I consider True Love. Then they split because one died.
Then the question of how you weaponize it?
Narrative only more or less. A knight given a token of affection by his love won't cut it. Lets just say it was a lock of hair. lets say he did tie it to his blade so it would always be with him. Then...
maybe it would count. I still doubt it.
Where this conversation is leading us is to one point that makes people uncomfortable.
It is rare enough that very few people are ever that happy. Now: It is your job as GM to explain to people in your gaming group what it is, how it works, and how common it is.
Also, let's weaponize it and cheapen it!
I think it fits +0 as a symbol. That it is rare and it is special. How did Dresden and Thomas both find it? They are characters of an author it doesn't have to be fair that the good guys always eventually win... The author also ruins their lives all the time.
Which brings up the uncomfortable fact that love hurts. (not a pun nor a weapon ;p)
So allow me to soften all of this with my standard disclaimer: It is your game - do what you want. Just don't expect hte forum to agree with you or come to anything resembling an agreement on True Emotions (love or otherwise) ; nor the rebate associated with it.
Though if I want to play devils advocate: which I always do...
Spoilered because it talks about the novels and is sort of a cause for debate.
Thomas and Justine found a loophole. Apperently Justine can still love Thomas a lot, but so long as she has sex with someone else before he feeds on her it is perfectly fine and she doesn't hurt him. Where's the True Love there? I can't see it. If her heart is truly straying when she has sex...she doesn'tlove him.
Now: I'll grant you - open relationships happen (I don't think that qualifies for True Love... but that's just me). I'll also say that Justine sleeping with another woman may be just fine with Thomas. Ii know many men wouldn't mind as long as they got to watch and or join in. That however is not the point. The point is...
If her heart doesn't stray - then the True Love still flourishes and she should burn him when he feeds from her or touches her.
To believe that a loophole exists like that cheapens True Love and in my opinion is the only thing Jim Butcher wrote that I didn't like. Maybe it was foreshadowing that Justine doesn't love him anymore... Maybe i don't give Mr. Butcher enough credit. I just didn't like it.