Shard of Starfall (PF1E in Midnight)

The world lost the capability it once had to share and pass down knowledge, skills, and art (books, libraries, universities, etc.) in a way that caused all areas of life and civilization to flourish.

If lost knowledge can be recovered and protected and put to use, perhaps the Sundering could be undone and Aryth would have the celestial allies it needs to throw off the tyranny of Izrador and his allies.

Living on a Gnomish smuggling ferryboat & barge was a relatively shielded environment, and father Finn and grandmother Oma Olga taught her to survive and earn a living through herbalist and sailing skills. She saw much less of her mother Idrun but after a fashion her 'earthwitch' type magic comes through knowledge imparted discreetly through her mother's Dwarven folktales.

Given her beliefs about what it will take to save Aryth once and for all, it would be difficult for her to have choose between preserving some written text and (as a healer sworn to do no harm including by inaction) on the other hand protecting someone's life.

Defending someone (or some text) you care about...she made a vow regarding texts.

Bogdan the Dorn blacksmith (she has reason to believe he betrayed her to a patrol hunting her as a magic user)

There is a redwood tree in a forest [which forest, TBD by GM] which is said to have been carved with a powerful inscription. If that carving could be found, and translated, and spoken aloud at the site, something wondrous (and/or dangerous) might happen to 'answer' the call.

Skyra Petra first channeled true magic to heal a fellow rebel PC to kill one of the Fell.

It does not manifest in a bombastic or visually impressive way, it involves making contact with a bit of earth/stone/or metal (Eschew Materials, so that's just her superstition) and a building-up sensation like vines of pure power climbing up through her soles and, as the power releases a feeling like tiny flowering buds bursting open. Afterward she feels lightheaded and hungry.

Aryth the world itself, as far as she can tell, is the source of her magic, fighting back against Izrador and his despoilers with her as its conduit.

Her most effective spells take the form of her mother Idrun's dwarven folktales: the stone that magically creates a nourishing soup, the stone that when blessed can slay the unnatural undead, cries for the very trees and underbrush to help you against undead or other foes that get answered (spells Life Trap, & Wilderness Soldiers) not legal.