A weakness where the worst element is that it recurs and recurs and recurs. Looking at the two elements, the effect and the discard condition, we get:

The effect: This is a fairly complicated weakness with 3 parts.

• First, you need to discard one of the 5 special events under Sefina. Losing one of her events can be trivial or damaging, depending on the event and situation. It's pretty common to have a card or two under her that aren't useful in that scenario or that you've used up your The Painted World and don't have a free action to get them into your hand; that doesn't hurt so much. Other times, you were counting on that Deny Existence or Slip Away and now what's the plan? Sometimes, you've drawn a lot and pulled all the cards out, so no discard!

• Second, if you can't discard, you take damage and horror, which is pretty punishing for a 5 Health investigator. Under normal circumstances, this isn't going to happen until you've drawn the weakness 3-6 times, but that can happen. and aren't all that great with soak, so Sefina doesn't have great options -- maybe Leather Jacket or Robes of Endless Night (2) and Lonnie Ritter?

• Third, you shuffle it back into your deck unless that deck is very thin. Without this, this wouldn't even be average badness, but here we are. There is very little mitigation -- she can take the basic Scroll of Secrets and hope to snipe it off the bottom of the deck. Quantum Flux can make your odds better.

All of these are very situational; draw this once, and it's no big deal; draw it 5-6 times, and it will wreck your day and probably the scenario

The discard condition: You kind of don't, except just before decking yourself.

This is a hard weakness to rate because it's so situational; everything considered, it's above average, especially if you have a draw-heavy deck or bad luck.

A bad weakness or the worst weakness? Let's see. Looking at the two elements, the effect and the discard condition, we get:

The effect: Wendy Takes 2 direct horror and removes her discard pile from the game. The first effect is bad but manageable; Wendy has 7 base Sanity and has ways to heal horror and/or soak future horror. The second effect ranges from mild to devastating. Depending on when you draw the Weakness, it can remove most of your deck, killing recursion tricks, shutting down Wendy's Amulet, and possibly leaving you in a very short horror spiral to trauma for decking yourself and more horror for drawing this again. There are not many was to mitigate the effects, with Rabbit's Foot (3) being probably the best way to dig for it early, maybe abetted by Drawing Thin or Take Heart to increase your failure and draw more cards. Of course, if you don't hit it early, this tactic may exacerbate the damage when the Weakness hits. If you have a Seeker in your party, they can help out with No Stone Unturned, but that's a lot of cooperative building, and none of these solutions are XP-cheap (especially since Rabbit's Foot vies for the Accessory slot with the Amulet, so you won't be doing them in the first few scenarios.

The discard condition: You do the terrible thing, then this card becomes your discard pile.

All in all, this is a way above average signature weakness, and in competition for the worst weakness, able to wreck a scenario or end a campaign.

Here's a review of the card as it actually works. No, you don't get extra icons in the mythos phase ("of this turn" implies that an investigator must be taking their turn, as compared to "of this round"). No, you don't get 2 icons and get to draw a card.

This card is a deck slot filler.

Treat this as a de-facto cantrip with restrictions on when it can be committed, and it's not that bad a card to include in a 0xp deck. Especially if it's a deck that runs Practice Makes Perfect but doesn't have enough Practiced trait skills (e.g. only Deduction and Perception). Better that a Practice Makes Perfect hits this card than nothing at all.

In a very situational pinch, this can act as an unexpected courage if the window is right — practically, a boost to your first evade or last investigate isn't terrible if you really need it and haven't gotten a chance to commit this on a test on someone's second action.

Practically speaking, a skill card that gives +1 draw on succeed is very usable, even if it has commit timing restrictions. Of course it's completely almost completely outclassed by Eureka! for the same effect, so most of the time you want Eureka! before you want this.

Another Enemy signature Weakness. Looking at the two elements, the effect and the discard condition, we get:

The effect: Enemy Weaknesses tend to be on the weak side, but this one is tailored to mess with Rita, since it gets an attack whether an Evade attempt succeeds or fails. There are weapons that do +1 damage (Like Fire Axe or the .18 Derringer), but that's still 2 actions to clear. The Ornate Bow is a very good choice, giving Rita a 7 vs 3 Fight for 3 damage, but Rita could really use her hands for clue tech and other things. Brute Force is another choice if you can boost her combat a bit to get a 2 up result. Like all enemies, of course, there is no reason another investigator can take them off her hands if that's not too much tempo loss for the team.

The discard condition: Kill them or get a friend to take a hit and Banish them to the far side of a large map or maybe get Handcuffs on them, but killing is the best choice.

Taking it all into account, this is an average signature Weakness, a bit more trouble than some of the other Enemy Weaknesses.

A relatively simple but damaging signature . Looking at the two elements, the effect and the discard condition, we get:

The effect: The sharp needle in Joe's Insight haystack, this is going to cost you an action, 2 resources, and maybe a clue. Note that you can play it even if you don't have a clue, which makes it considerably less damaging. Joe needs to keep 2 resources on hand until this gets drawn, and it could cause an AoO if he is engaged when it comes up, but, despite the nasty effect if it fires, this is not a terrible threat. There is no particular mitigation, beyond making sure you have those resources or a quick way to get them. If Joe has somehow managed to translate the Cryptic Grimoire, he can play this fast. That Tome would generally help Joe, even if it's not hugely feasible for him to translate it without a cooperative Rogue or a lucky draw of the Dread Curse Weakness during deck building. Farsight could also help, but it's got a high opportunity cost for Joe. Other than that, there aren't a lot of card interactions. You can't even troll your party by playing Eidetic Memory, since Unsolved Case is removed from the game.

The discard condition: Another "one and done" Weakness, and one that removes itself from the game after playing, so it won't recur, even if Joe decks himself.

Summing up the facts, this is a way below average signature Weakness, in competition to be the easiest in the game.