It's nice that it doesn't cost resources (so you'll have more left to pump stats) and icons are decent but Mystics aren't flush with cash and have better uses for EXP. It'd need to cost one less EXP or be permanent free like Streetwise(4) to be worth considering.
Having arkham player cards in Polish, English and Italian it is really fun dealing with these encounter cards. I purposely take 1 italian and 1 polish copy of, let's say, Magnifying Glass (Lente di Ingradimento) and have some fun :D
Great card! Have a question on it though (wasn't sure where exactly I should ask)...
On the second fight (on both the base and upgraded cards), can you add another card with the bold FIGHT option, like "Monster Slayer"?
The card is not so situational as it seems. Really what your paying for is 3/3 soak body slot. It can cancel a specific Type of treachery that you have to draw, but it does that at a cost of 1/1. The treachery will have a worse effect but not likely twice as bad as 1 damage and 1 horror. Just use it if you want the armor and the other part is a solid upside that certainly doesn't need to happen for you to be happy.
2 xp card for a fast Old Book of Lore use/Eureka effect for each player, but you can't always control when it happens because it's a dilemma. That sounds expensive, but possibly justifiable.
But, you also get all of the weaknesses you don't choose back for free! And you remove all of the non-weakness cards (which you put in your deck, so you probably want them, with the possible exception of a few signature cards if you don't build your deck to use them) from the game instead of discarding. And the card is Survivor, which is the class who can recur things.
The deck-thinning means you probably don't want to recur it, so it's a single-use event for 2 xp, with drawbacks.