This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
勨 combines 象 (elephant, image) with 力 (power). The exact historical development is uncertain, but it likely originally expressed a concept related to strength or movement, given the kun readings ゆる.やか (gentle) and うご.く (move).
The left side is 象 (elephant) and the right side is 力 (power). Imagine an elephant using its gentle power to move slowly and smoothly.
For ヨウ, picture a yo-yo moving gently up and down: yo -> ヨウ, and the elephant's power moves it smoothly.