So, what went into making All For One's giant Akira arm?
- Springlike Limbs - store and release force
- Kinetic Booster x4 - increase movement
- Strength Enhancer x3 - increase strength
- Multiplier - grow multiple limbs
- Hypertrophy - increase the size of the muscles
- Rivets - form metal on the body
- Air Walk - hovering
- Spearlike Bones - sprout spiraling spikes from the body
As for the two powers' names, "All For One" came first, and refers to hoarding all the powers for just one person; "One For All" was named as an inversion of that, representing passing the single ability along from person to person. Which seems like it should be straightforward and easy to remember, yes?
Unfortunately, the way One For All works is by collecting a bunch of powers and passing them all along to one person at a time, meaning it could just as easily be called "All For One." Meanwhile, All For One can give one power away at a time, to all people, so it could have been "One for All."
It's easiest to remember that the names aren't about the powers, but about the people wielding them: the user of One For All believes in doing their work for the betterment of others, while All For One believes in hoarding everything for himself. It's "one person for all people", not "one power for all people."