shine, light
暉 centers on radiance: shining light, brightness, or a glowing appearance. Its meanings are straightforward applications of that luminous idea.
暉 combines 日 (sun) with 軍, which likely contributes the sound and may suggest a spreading or encompassing quality, giving the idea of sunlight shining broadly.
The sun 日 on the left spreads its rays over the army-like mass 軍 on the right, making everything shine with light.
For キ, imagine a key made of pure light that unlocks the sun's shine: key -> キ, and the sun 日 radiates brightness.