This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 芺 is uncertain. It visually combines 艹 (grass) and 夭, but the original meaning and component function are unclear.
With grass 艹 above and 夭 below, picture a young sprout bending in the wind—its meaning is uncertain, but it may relate to a plant or something delicate.
For オウ, imagine an old man saying 'Oh!' as he tries to identify this mysterious grass: Oh -> オウ.