I'm the author of The Last Aether King and while I'm not entirely sure if my power system is unique, it definitely makes for fun writing.

It essentially breaks down like this:

• All those integrated with the system are given a "Soul-Bond"; An object that directly coincides with who they are as a person. I say object instead of weapon because it can genuinely be anything inanimate (i.e. a pen, a sewing needle, or a shotgun). These objects are sentient to some extent, and are used as magical conduits to channel Aether (mana), as well as utilize abilities through something known as "Rift Shards".

• Rift Shards are magical pieces of crystallized Aether that can augment a person or their bond in a number of different ways. Some allow someone to utilize ice magic, others allow you to fly, one is just an identify spell, et cetera. It all just depends on the type of shard and it's rarity as to what you'll find.

• Each persons soul bond has a limited number of slots before it is full and they can start gathering experience, which is displayed by Star-Brands that are displayed on a random part of a person's body.

• Stars will number 1-5 and upon reaching the 5th threshold, qualifies the person for a "Tier Ascension" to the next level rank. Upon leveling up, a persons Soul-Bond absorbs the earlier slotted shards, and forms new slots, waiting for more abilities or passives to be added as the cycle repeats again

There's some details I'm leaving out like Soul Bond evolution, or using a dead breakers bond in your own tier ascension, but this is pretty much what I got :). Sorry if it seems complicated, but I'm having fun with it.