Hmm...would it be possible to see the potential options before voting? I feel like that would help decide things.
Alright
Here's a few sentences about each potential empowerment method
Mantling: The user takes on the 'mantle' of a specific mythological figure and gains a fraction of their abilities. With training, this fraction can of course be increased.
Eidolism: The user summons a magical being to fight with/for them, with the being starting out weak but able to grow stronger in the future.
Mythblades: The user wields a mythblade, a weapon with a mythical beast sealed inside of it, bequeathing the wielder with unique supernatural pwoers as long as they wield that mythblade. A person is only ever able to use one mythblade at a time
Wargame: The user brings a minature from one of multiple popular (fictional) wargames to life temporarily. With training, the number of minatures that can be 'animated' increases.
Warformes: The user shifts into a specialized warform, a second form built for combat, normally with a few supernatural abilities centered around a 1-2 word theme. With training, it is possible for a warform to grow stronger.
Coregrowth: The user has a 'core' aspected to a specific facet of reality, and by 'feeding' that core by taking in energy related to their core's aspect, they can perform supernatural actions related to that aspect.
All of these empowerment methods are, on a worldwide scale, incredibly broad, but on an individual scale, pretty narrow.
Mythblades and core aspects and warforms and eidolons and mantles are incredibly varied, but you only get one of them, similar to devil fruits.
The wargame empowerment method gets around that limitation, but is weaker as a result.
I hope that helps