@Timemaster Sure thing!

Origin and accessing magic: Magic is drawn from one of two places and subsequently has two names: Arcane and Divine. Arcane magic is drawn from one's spirit and the potential one has to command it is something you are born with. In this regard, not everyone is a candidate to to be a great wizard and a strong spirit to control the Arcane is something you have or not. Think of it as a natural gift or skill. That being said, it is difficult to control and is potentially very dangerous if one does not receive training. This danger has made many afraid of magic and is the core reason for a number of inquisitions and the widespread purging of mages in the land of Aerion (especially in the land of Ethora) leading to is rarity. However, Mage's guilds still exist and many students of Arcane magic go there to learn, control and develop their abilities.

Divine magic is drawn from one's faith in a certain divine being, whether it is an established figure or not (meaning it is does not have to be one of the major figures from Aerion's religions, which I can provide, and could be "made up"). Many Priests fall under this category for example. Divine magic is less dangerous and primarily used for healing and the like, though it can be used to curse others for example (if the patron deity is "evil" or "dark"). Divine magic is still fairly rare as to access it someone must have strong faith in a figure and like arcane magic be well trained.

Staves and augmenting magic: Staves, rituals, and other tools can augment and strengthen magic. Staves are usually used to channel, strengthen and help control magic, rituals and ceremonies can focus or strengthen it and other tools like wands and books do exist and do much of the same as I just said.

Rarity and use: Magic is increasingly rare because being a mage, wizard or any title is a stigma that often leads to imprisonment or worse death. People do not like magic for it disturbs the peace and is a constant threat. Magic is very powerful and power corrupts. Therefore, using magic in a public space is not a good idea for example, as you will likely be captured or killed on the spot by the townspeople or if you are lucky, the local town guard. Magic is often confined to the home or in the case of divine magic (which is generally more accepted), a church or shrine.

However, Raelus is one country where Arcane magic is more accepted, as the government makes extensive use of the offensive properties of Arcane magic in its military conquests. In this regard, mages are more of a resource however. Miracia is another country where magic could be found, as well as Palaven.

I hope this helps! Let me know if you have any other questions.