frontlet
鍚 refers to a frontlet, an ornamental metal piece worn on the forehead of a horse, so its core idea is a decorative metal forehead plate.
鍚 combines 金 (metal) with 昜, which likely contributes the sound ヨウ. The character specifically denotes a metal frontlet for horses.
The left side 金 means metal, and the right side 昜 looks like a shining sun over a horse's forehead. Imagine a shiny metal plate on a horse's head catching the sunlight.
For ヨウ, picture a horse wearing a frontlet that glows like the sun: 陽 (よう, sunshine) -> ヨウ, and the metal plate shines brightly.