This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
暚 combines 日 (sun) with 䍃, a component of uncertain origin. The exact historical development is uncertain.
The left side is 日 (sun), and the right side 䍃 looks like a container. Picture sunlight pouring out of a vessel, making things bright and clear.
For ヨウ, imagine the sun 日 shining brightly like a yo-yo bouncing up and down: yo -> ヨウ, and the light is radiant.