"Magic is a curious power that manifests differently. Some pick up spellcasting with more ease than others, though some have suggested that magic is possible for anyone to learn. No one in Tormyra would admit to thinking of that hypothesis, of course. Those nobles would be scandilized if magic were more available to the common folk!"
"I think I put a piece of my soul into my music, and that act is how I cast magic. My cousin's from one of those magical bloodlines, but she describes magic as being a part of her, while my best friend says she has to sit and study her books every night and have the right materials."
"The magic of the gods is not like the magic of mortals. Our magic is a gift from our deities. No! Not like those who make deals and pacts with those ... beings, for their magical abiities to be enhances! We get ours from actual gods!"
"Hm? My apprentice doesn't seem to be quite like me in how he uses magic? So? I have the most extensive library, anything I struggle to teach in person, my apprentice can learn from the written words of mages before him. And their experiments. Or his own experiments."
"Hah, you want to try and travel through time? You'd have to be a god to do that - and you'd likely piss off every single one of them. Zyrian would certainly be annoyed if people were messing with time as well as defying death. Wait, you're serious, aren't you? Time is not our domain."
Magic is intertwined with one's soul, though not everyone has as much magical inclination as to be of use, and use requires some kind of training. Some people require less training than others.
There are ways of amplifying magic, naturally or less naturally.
The Gods can also amplify one's magical talent, through direct action such as selecting one to act on their behalf, or through artifacts left behind.
So, you do have the possibility of magic universally distributed, in principle. Then some families have it developed more than others, and methods of study grow in different directions. Nobles are often (or necessarily ? ) mages, what is an interesting option. Always seems odd to me how most scenarios keep the chief and the shaman separated in different characters whit no plausible explanation for this. Why those people able to control the storms, read minds, live dozen times longer than normal and kill enemies miles away with demons summoned from one metaphysical abyss or another don't just take the throne or start a new realm with voluntary followers? Why only your typical Evil Warlord seems to realize the convenience of combine metaphysical and political powers? I wonder how powerful is magic in this scenario? As good as an honest long bow, about as decent as our average nuclear bomb, or something in between?
Magic is not actually universally distributed, though magic and soul-stuff are the same material, some people are more able to tap into their own magical potential, and then have more control.
In answer to the power of magic, magic is as powerful as both, depending on the user's control. For "magical power" the definition of "Powerful Mage" is more based on a mage's ability to control their magic. A mage who only throws town-destroying spells is considered weak for not having the ability to refine their spells, while a mage who only casts small scale spells are weak because they're unable to scale their spells to a higher level.
In the Kingdom of Tormyra, specifically, the noble class are mages because their society is based on how powerful of a mage you are, but in other parts of Soplas (the land mass) and Corive (the world), mages are at different levels of society and may be commoners as easily as rulers.
As for why mages don't rule everywhere, they're generally outnumbered by nonmages and typically mages have to defend themselves from nonmagical attack methods. The Kingdom of Tormyra (and some other areas) do have ways of nullifying magic and spell casting (usually used to deal with improper uses of magic).
Thanks for the clarification Lyraine Alei. I suppose there is an aspect of how magic influences society that has to do whit the top possible achievements know to be possible. Of course, makes difference if the average practitioner can do something more or less relevant as well. Still, the way we see our world and human species in it do changed considerably when a nuclear bomb was used from the first time; despite the fact that the average human had little to no chance to get an H bomb, or know a neighbor who had one in his garage. Another factor of magic I meditate about was what loyalties the average user of magic is supposed to have, that came from being a user of magic. But in Sharitarn very few individuals can even use spells in magical objects, a small part of those can actually make spells, and no one goes from mere_and useless_ magic potential to one of those categories: takes a mentor or more than one. By comparison situation in your world seems far more complex. Self didacticism opens the possibility of more anarchic types walking around with great power. Likely most powerful people would still be loyal to the same values the average non-mage in the same society holds dear. Family perhaps, maybe nation too. I can see mages supporting each other in some circumstances, but my impression is that take the side of other mages would not be the most likely choice for most users of magic.
I'm glad my system seems to be more complex. I was never a fan of the idea that "all mages" or "all x type of mages" are one way or another, so I wanted to make my magic feel more personal. Some of how I like to think I did this was by describing how mages who use different methods are capable of teaching students who may not share their means and tools for magic (though a D&D Wizard may struggle with teaching a D&D Bard or vice versa, but it's still possible, and a Sorcerer who generally "does" magic without a strong need for studying may in turn struggle with with a student who needs to take a spell apart to fully understand it and then to cast the spell).
Loyalties of a mage are generally the same kinds as loyalties a nonmage may hold based on that mage's culture or the culture around them. One region encourages a divide between mage and nonmages. At the same time, another discourages that divide in favor of everyone being able to contribute to their social group (family, community, town, city, nation, other group identification, etc.).
As this article is an overview of magic on Corive, I tried to keep it from being focused on how just one region's culture views magic.
Yes, I see how the system you show us here provides precious opportunity for interaction between characters. Particularly in stories about journey for enlightenment , and reaching maturity. The sort of tale where mentor/disciple relationship shine their most rich colors. There is something a bit distasteful int the notion that some sorts of magic are "good" or perhaps magic itself "evil", and stories where people divide themselves between those in favor of sell their souls to a particular magical power and those against to do so. Even considering that a lot of my favorite fantasy scenarios do has that attitude toward all or at least some magical schools. Is a bit like if the nations pro-helicopters and fire-guns decided to join forces and stand together against the nations which use helicopters and fire guns in their military forces. The idea is silly, I suspect one could tell great stories developing the premise and nevertheless the premise in itself would still be silly.