She nods.  "I don't think Culpeper Cut would care about who you pinned that title on per se unless it actually managed to build a working model of human cognition sometime this century, so, I wouldn't.  But that's good to know about."

"Mhm. To the library at last then?"

"Yes please."

The whole building, architecturally, seems sort of torn between modernity and a very Old Money feel- Portions are smooth, white, and chrome, while others have landscape paintings with artful filigree and oak inlay.

The library leans fairly hard into the 'old money' side of things. The floor is patterned wood, the chairs are plush, there are chandeliers and latin mottos. It's not a vast museum-like library, much closer to a small local one, but definitely fancy.

"Welcome to my domain," says a woman in obvious raiment, positively nailing the 'librarian' look, with a pretty Asian face, blue hair in a neat bun, a purple/white vest sort of garment with shining buttons and stripes, elaborately patterned silk cape glittering with silver, shaded glasses, black gloves that flare into a star pattern at the wrist, and probably more behind the desk. "Miss Riley, is this Luna, Maeve's five o'clock?"

"Indeed. She wants to browse while she waits. Luna, this is Madam Pen, who prefers to be called that or 'the librarian'. Madam, Luna, a newly mantled spirit bearer - or perhaps spirit guardian?"

"Very good. You won't be able to check anything out today, and please don't try to re-shelve things yourself. We only keep books relevant to the life of a spirit bearer here, though that is a bit broader in some ways than some imagine when they hear it. May I help you find anything?"

"Yes, please; where's the index?  I know I don't know enough to know what I can know I don't know, just yet, madam librarian; given that knowledge is power, I'd like to rectify that glaring discrepancy with all due haste!"

...She somehow manages to put a Clara-tonne of energy in to her library voice, which, she thinks, is a feat actually worthy of an outfit upgrade, unlike simply winning a fight like a blunt instrument.

"Physical and digital," Madam Pen indicates a desk off to the side. "We use an adapted version of the Dewey system. The broad categories would be history, monsters, spirits, human magic, and other. I can offer recommendations if you tell me what you wish to learn."

"...What I'm immediately interested in is the stuff that's known to bite newbies in the ass, pardon my language; let me write down some of the farther-future topics."

In short order, Madam Pen has a Post-It with "not-becoming single point of failure/replicability of unique magics, force projection (Can't be everywhere at once; want to), what's with outfits/weapons anyway + I have too many spears, learning/developing new elements?, evidence of monster sapience/lack-thereof"...

She considered more, but she's done for her first research-binge.

"There's a wonderful book titled 'The Unfathomable Power of Common Sense, Applied to Magic' by Christine Cooper, who published it under her original name rather than a magical one. I recommend it to anyone who asks for anything like your first question. Can you elaborate on replicability of magics? Do you not want to end up the only source of some spell? In terms of force projection, 'Anti-Monster Tactics and Risk versus Reward' by Steel Helm. The nature of outfits and weapons is a deep topic but 'What's in a Raiment' by Blood Ribbon will get you started. For the last, 'The Thinking Foe' by Fleur D'or takes it fairly comprehensively despite the martially minded title. I think she wanted to get 'stab first' type girls to think about it."

"I don't want to end up the only source of a spell, no.  I also want to avoid letting others' useful spells 'die out'.  But right now...that first book sounds like the thing I should focus on, then 'What's in a Raiment'."

She'll write down all these books for later, though!

"Thank you, Madam Pen!"

"Of course. Just treat the books well, alright? As for spell specialization, good for you to think of that early on, but it's not easy. Exact duplicates are rare to nonexistent."

She rattles off Common Sense's location.

"To wilfully treat a book poorly is the sort of thing I'd call a sin, ma'am."

Alright!  To the books!

The Unfathomable Power of Common Sense, Applied to Magic has the following to say, in fairly more elaborate and detailed prose, with examples: 

• Don't fight monsters without backup
• Don't try overly flashy moves when sensible ones will work
• You're not immune to car crashes or other forms of accident
• You're still squishy when not raimented
• Don't fight monsters without backup
• Remember that environmental damage, like say, forest fires, exists
• Don't piss off spirits, most won't bite your head off but be respectful
• Being famous can be a curse, consider how public you want to be
• Fire magic ignites things. Water magic can erode foundations. Wind magic can send debris flying. Etc.
• Don't fight monsters without backup
• You should get a feel for various levels of unwinding to know when you're at your limit
• Control first and then power, always
• Ordinary humans are still squishy, and so are most buildings
• Learn about the common kinds of monsters and slang - goblins, beasts, slimes, swarms, ambushers, infiltrators
• If you don't recognize a monster, back away slowly and call for help
• Don't fight monsters without backup
• Keep in mind that most of your magic will not be permanent, water vanishes, heat dissipates, bindings dissolve. The major exception is healing, usually. But observe your own powers to find out.
• If you have the itch to make something, be careful, enchanting can be very draining
• Also be careful with whatever you end up making, who knows what it can do
• Try out new spells, new combos, new items, etc, in a safe place/on consenting subjects/with healing or whatever available, if possible
• Genies are really stupid, they mostly won't monkey paw you but you can monkey paw yourself, so be careful
• Overconfidence is a slow and insidious killer, think about the risks you take, always
• If you think you can use magic to fly, if it's not a native spell it's harder than you think
• Remember when doing parkour or flight or anything that hitting the ground will hurt, a lot
• Let cops handle mundie criminals for the most part they have de-escalation training and nonlethal takedown training
• Oh, also, don't fight monsters without backup

Yep.  Don't fight monsters without backup, and mind the collateral damage.  ...Sylvia's conjuration not working for repairs properly is something she might not have otherwise caught, though; good book.  And yeah of course flight is hard, she doesn't have arbitrary vectored thrust!  ...That said, now that she's thinking about it, she could probably use water 'balloons'...

Also - enchanting?

...Oh, the cops have de-escalation training, yes, that totally explains FUCKING KANSAS -- 

'Breathe.  Tipping over into unrestrained anger kills you.  You need to be alive to fix things.  Therefore you must breathe.'

Okay, she's done with that and looking into getting herself a ranged weapon now; What's in a Raiment, please, library?

The book is easily enough found. Raiment is a magical construct! It sort of acts like it has mass, threads, particles, but it doesn't. Raiment under a microscope, like monster parts under one, look like dozens of different things - mostly what you expect them to. It pretends to have properties like mass, heat capacity, shear strength... But just doesn't, not consistently, raiment experiments don't add up. Raiment does a pretty good job of pretending to be clothes, albeit ones that always fit perfectly and never get too warm or stained. Something deep in the nature of human magic just seems intrinsically linked to clothes, maybe because they're what separated agricultural humans from the early dark and terror?

Your raiment tends to be things that both you and people around you would find pretty and cool, and most people can't edit it freely, only with focus and effort and only to an extent. It can change dramatically after important life events. The very earliest magical girl there is archaeological evidence of (an extremely rare and lucky find, found protected by ancient ward stones in a tomb!!!) is from approximately 600 BCE. There's paintings and Egyptian writings of a spirit bearer, commonly called White Tigress, who "was chosen for the house of light" and fought "the rotting crocodile of the south"; Her outfit included tons and tons of white flowy cloth and egyptian-style ornaments that line up closely with what the people of the time depicted the gods wearing, and it looks like they actually considered her basically a god, much like actual spirits.

Here's some cross-cultural raiment comparisons!!! Lots of yukata and hanfu and qipao in Asia, basically things that are culturally high class everywhere throughout history though getting more uniform after cultural crossover in the last few centuries, with the commonality of getting continually fancier and more elaborate with increasing magic power. Is raiment a side-effect of magic? A requirement? You can't do magic without manifesting it, but restoring one's raiment is an automatic, reflexive action, even more than the regeneration. Magical Girl Sapphire Eye attempted to focus on not restoring her raiment, and also using her more powerful clarivoyant spells at the same time, and couldn't do it. Raiment expressions have tendencies in terms of what they mean for powers or personalities, but this is usually vague and metaphorical at best; Here's some of the trends and some case studies.

And...this doesn't tell her how to change it.  Dammit.  Fine, she'll try deriving it from first principles.  Step one -

-- Acquire a spotter, first.

"Madam librarian, I don't suppose you'd know if there's anyone who'd be better placed to help me make better use of having half-a-dozen spears tucked away in 'raiment I'm presently not wearing' than just asking someone I met - oh, about an hour, hour and a half, maybe two by now - anyway.  I have too many mostly-identical spears cluttering my metaphorical inventory, and I would like to fix that.  However, one oughtn't experiment unsupervised, and I certainly haven't the faintest clue what one is supposed to do to shift a raiment other than 'believe very hard that it shall be so'."

Still.  First step, imagine, expect, reify.

The librarian gives a very Librarianly eyebrow-raise. "You're going to have to clarify what your plan is. Are you speaking of changing your weapon, or changing your clothes? One's weapon is, technically, not raiment."

"One's weapon.  Though possibly also my raiment.  ...Ah.  I'm going to need another book, aren't I?"

"Thankfully there are plenty. Yes, weaponness is different from raimentness, though I personally think we ought to have better jargon. Weapons tend to be easier, they respond to use of potential well enough, unlike raiment."

"Honestly, just make a supercategory of regalia, and then you're golden.  Or maybe genericize raiment, and put 'regalia' where raiment used to be?  It depends, I suppose. Anyway.  Yeah, there's like...I have way too many spears."  One spear, two spear, red spear, blue spear...Just to show what she means to the librarian, of course.

"...That is unusual. Do it again? Oh, nevermind, I see, interesting. Common Sense wouldn't have gotten into potential and expending potential, do you know that concept yet?"

"I have any idea what it might be, but hearing it from someone who definitely knows is a better idea."

"The common understanding is that spirit bearers grow in the direction they dream, strive, and practice for. This is not, strictly speaking, inaccurate, but recently another understanding has been put forward thanks to one of our researchers. The evidence is suggestive rather than conclusive, but under the," (a near imperceptible twitch of a frown) "Experience points theory of potential, a bearer can accumulate the capacity to develop new aspects of their magic to an extent. By not pushing for new capacities for some time, they can then grow a great deal at once. Have you experienced a sensation of pushing, as if your magic doesn't quite seem capable of something, but you try very hard and manage it?"