beautiful, splendid
懿 centers on a refined, admirable beauty: something splendid, graceful, and deeply good. The given meanings of beautiful and splendid both point to this elevated aesthetic quality.
懿 combines 壹 (one, whole) with 恣 (arbitrary, self-indulgent), but the historical development is uncertain. The character is rare and its exact origin is not well documented.
The left side 壹 suggests unity or wholeness, and the right side 恣 contains 心 (heart). Imagine a heart that is whole and pure, radiating a beautiful and splendid inner quality.
For イ, picture a beautiful eagle (イーグル) soaring splendidly: eagle -> イ, and its grace embodies the kanji's meaning.