It is not immediately clear if it is possible for Luthien to look more horrified, but she seems to be giving it a really good try.

"All of our lore contends that the destruction of the Fae is impossible, but it seems there is much we do not know about your world."

"Yeah. There's a lot different. And I don't even know for sure, but... Anyways, it's - part of why I'd like to try and see if the joy song helps turn them back into magical girls sooner rather than later. I'll also stop using grief seeds outside of emergencies, just rely on Luthien's joy song."

"That just makes our task all the more urgent, I think."

He once more stores Anglachel away, and draws off the wall another blade, far fairer than the dark blade of Eol, but without its dark sense of power. It shines like the frost, and the air chills as he takes it into his hand.

" - I still might want to try Anglachel, my invulnerability's a lot more comprehensive than my barriers. But we can start with other blades if you think that's better."

“If a lesser blade would suffice to harm you, it seems foolish to test first with Anglachel.”

It turns out that, at least in Mablung’s hands, most of the swords can break her lesser barrier, but it’s usually fairly hard. Only a handful can damage her stronger barrier, and on those Mablung refrains from powering through and shattering the barrier entirely. Five of these blades are rather similar, which Mablung attributes this to their makers; they’re forged by Fëanor, Curufin, and Celebrimbor. There’s also an axe and a hammer he identifies as the works of the Khazad of Nogrod, and a sword called Narsil forged by a smith named Telchar; nothing else suffices against her stronger barrier.

She wants to test anything with strange effects against her skin, too - it's possible even if something can't cut her it might be able to act on her otherwise.

He passes her the weapons she wishes to try. Most of them fail here as well; or achieve little; the chill of the first sword can be felt, but it fails to harm Sue, which is a trend that continues among many of the blades. The one that shines like a beacon with the light of the sun does succeed at temporarily blinding her at full strength, but it’s nothing she can’t easily heal. The most interesting result from these weaker weapons is a chain that binds Sue’s limbs beyond her ability to readily escape, but it’s in turn easily deflected by the barrier should she try.

She still wouldn't be surprised if she could do something about the chain, but she's not really willing to make a blast capable of damaging their infrastructure. Still, magic chains: something to watch out for, since they can be as strong as or stronger than binding ribbons. (Her plan for if a hostile manages to chain her is honestly currently 'fly straight up, hope rocket speed trumps whatever anchor they have and that she can handle being out of the atmosphere better than they can'. Not really an option with magical girl ribbons, but her limbs being bound with the chain doesn't stop her from flying around, so.)

"So. Magic chains can potentially be a problem, and I'm looking at - trapping being the biggest common threat. So I definitely should pretend to need to dodge stuff, so anyone coming after me has less incentive to bring a magic net that's anchored well enough I can't just fly off with it."

“It would probably not go astray to wear armor as well, if you find a set you like; even most of the enchanted stuff wouldn’t do you much good, what with how hard to injure you are, but it should redirect attempts to harm you to hitting weak spots in your mail rather than pinning you down.”

"That's a good idea. I can change my raiment so it looks like armor; it can't be damaged the same way I can't if I don't want it to, and other clothes get - folded away - when I'm in my raiment anyways." 

Mablung fetches one of the finest they have, forged by Fëanor in Valinor, to serve as a model.

”There are a few later works of his and Curufin’s that might better still explain your invincibility, at least to the spies of the enemy, but none that are not already accounted for among the Noldor.”

Of the weapons that Mablung manages to use to break the stronger barrier, none can injure Sue; a few seem to react differently to the barrier, but it becomes clear that Sue’s invincibility is really quite comprehensive. After seeing the last of them, a dagger forged but Celebrimbor, fail to pierce Sue’s skin, Mablung frowns in thought, but goes to bring forth Anglachel.

Some of the stronger ones do cause the sort of black shimmering over her skin around the point of contact that Sue identifies as a something that sometimes happens when she tanks powerful blasts.

"Mind if I hold it? That'll make it easier for me to pull back if it does cut me."

He hands over the blade, sheath and all. It’s got a weight to it, but it’s not so heavy that it’s difficult to lift.

She draws it, keeps the sheath handy, and tests her thumb against the blade.

A solid shield of glowing black springs over her thumb, stopping the blade, causing a thin shimmer much farther from the site than prior experiments. The shield pulses, and is very, very clearly magical - and warm, physically and emotionally. (There's an echo of emotion, separate from Sue or the blade, curling protectively around Sue.)

“If you did not wish for me to harm you, why did you swing me at your hand?”

The voice is cold and clear, somehow sounding completely fitting for the blade within her hands.

...Okay, telepathic sword. 

Just to the sword: "You are the greatest of swords I have heard of. I thought that if any here could injure me, it would be you, and I needed an assessment of my vulnerability. Does intent change your ability?" 

“It affects you. Your barrier responds to desires, and is resistant being pierced by those who do not deeply desire you to be harmed. I know you not, and have no care for your injuries; if you do not desire that the shield fall, it will not do so by my power.”

"Hm." It's easy enough to twist her thoughts towards her old anger at her sister, the sheer spite that had her thoroughly testing the invulnerability as a kid. It's a familiar rage. Like an old, worn coat. 

The sword jerks forwards, slips through the barrier, which throws sparks -

And into Sue's skin.

She hasn't felt physical pain in ten years.

It's... Interesting.

"There you go."

"Thanks for the tip." She pulls the blade back, takes a deep breath to calm herself down, and looks to Mablung and Luthien. 

To them: "So, it couldn't cut me at first, but once I started strongly intending to get past the barrier it worked. Also did you know the sword can talk. Because it was the one that informed me about the desires overpowering the invulnerability thing."

“I did not know that, but I’m less surprised than I could have been. I suppose I didn’t think of how literal Queen Melian was being when she said he put part of himself into the blade. 

“Do you think someone could do the same with another blade, or would you only need to look out for Eol himself?”

" - I think it'd be harder without... A specific magic, I've angered plenty of people who haven't hurt me, even if I've tended to avoid fighting high-capacity people. But... The way my world's magic works I wouldn't be... Too surprised? If someone who cared about hurting me more than - the person who wished for my invulnerability - cared about protecting me, managed to blast through it. So it might be a 'anyone angry enough and equipped with magic'."

”That could be bad. Mom remembers what The Enemy was like, back when the world was young and he was still called Melkor, and he hates everything in creation. The Powers don’t think like we do, but they’re... bigger than we are, in many ways.”

"Yeah. I don't know if that's - specific enough, or if the way the Powers process emotions - counts as close enough? But it's not something I want to risk."