bright
暻 centers on brightness or radiance, often describing clear, luminous light.
暻 combines 日 (sun) with 景 (scene, view, also associated with light), reinforcing the idea of brightness. The exact historical development is uncertain, but the components suggest a semantic compound related to sunlight.
The sun 日 beside 景 (a bright scene) makes the whole character shine: 暻 is bright, like a sunlit landscape.
For ケイ, picture a bright ray of sunlight shaped like the letter K: K -> ケイ, illuminating the scene.