Badgerfrog
Dreamer
Swords are cool tho....and my magic has a ghost sword. I am humbled, my good sir or ma'am(Or both or neither), and I humbly request your feedback on my system, if you would be so kind.
I'm a dude, man.
The first thing I see is that your post is pretty focused on the capabilities and limitations of the magic system itself and somewhat its history.
Purely as a magic system it feels pretty fleshed out, as though you have a good idea in your head of how it would work in real life and why it functions the way it does.
One thing I'd maybe do is "Why" it. Just ask "Why" about every little detail and question the answers you come up with even further until you get really granular. That'll help develop reasons for things to be the way they are in your world and help you flesh them out in a way that allows you to build upon solid foundations.
You definitely don't need to add this all to a story or even write it down(it does help though), so long as you as a writer know the answers, and understand how various metaphysics, interactions, and histories affect a world.
Caution: Feel free to ignore the below pedantry if you want.
Might not be what you're asking for, but another thing that immediately stands out to me is the most boring but also a crucial part of worldbuilding: formatting.
Forget sharing with others, just for the sake of my own sanity, the moment I start worldbuilding, I focus some time on making it legible and super organized so I can find what I'm looking for easily and add stuff in when ideas strike me.
I Start With One of These For Major Elements of Worldbuilding Like Magic(Font Size Changes Optional)
Then Go Here For Each Major New Type of Magic
Then Further Sub-Headings Can Be Like This For Stuff Like Magical Subtypes
Then Give Us A Specific Form of Magic
-Then:
-Organize:
-Standardized:
-Elements:
-Like:
-This:
Italics For Sub-Notes and Reminders Too!
Repeat, Etc...
Then copy and paste the format, and you can just fill out each blank for every different type of magic or whatever other worldbuilding element you need to add.
For your post, this might look something like:
Magic
Blade
Rarity:
Nature:
Type:
Requirements:
Limitations:
Flaws:
Subtypes
-Sword:
-Spear:
-Etc...
Or somesuch
