change, be of use, reach to, do, try, practice, cost, serve as
爲 centers on purposeful action: doing, making, or trying something, often with a sense of change or transformation. The ideas of serving as, being of use, or costing something are natural extensions of acting toward a result.
爲 is the older form of 為. It is traditionally explained as a hand 爪 guiding an elephant 象, representing the idea of doing or making something happen. The lower 灬 is a fire radical that replaced part of the elephant shape in the modern form.
The top 爪 looks like a hand reaching down, and the lower part resembles a creature or shape being guided. Picture a hand directing an elephant to do work, representing purposeful action and change.
For イ, imagine the hand guiding the elephant with an easy (イージー) motion: easy -> イ, and the action becomes effortless.