We could make up a few more magic systems for you if you wanted, though how one goes about making magic systems is very different for this kind of RPG.
If you are writing a novel or making your own setting, it might make sense to start with the magic system and then build characters around how they interact with this center pillar of the world.
The sentienls world already has a huge grab bag of different types of magic though, so we would argue that in this case its best to start with the expression of the powers. That is to say, decide what you want your character to do, then come up with how they do it, and then build a character around the what and the how.
This works for any power source, not just magic
Lets say for example you want to make an electric magician who can throw lightning at people because everyone wants UNLIMITED POWAAARRR.
So now you got the basics for what the character can do, figure out how they do it.
Possessed by a lightning spirit from an island somewhere tapping into primal energy?
Result of the experiment of a mad scientist that specalizes in biotech mixed with magic, some kind of "Biomancer" if you will, that created an organ that can store and discharge electricty?
Reality warper who had a brief contact with Wager Master and who has a fundemental misunderstanding of what "electrolytes" do, and so can command lightning so long as they have a sufficent supply of gatorade?
Then you can build a character around the power.
How does interacting with an ancient spirit inhabiting the same body affect your character? Does it still bear a grudge against the British for invading its home centuries ago?
Are you some kind of "Skin baby" as it were? A simulacrum of a living human created for dark purpose? Or are you a person who bought super powers from a shady guy in a cloak? What do you do if that organ gets injuried, and you need it repaird?
What happens when you lose your magic feather? Can you still use your powers but your mind slowly loses purchase on the "real" world as you defy the laws of physics? Do you need to keep coming up with more and more eloborate explinations to explain your powers to protect your own sanity?