right, proper, propriety
韙 centers on correctness and moral fitness: being right, proper, and in accord with propriety.
韙 combines 是 (right, correct) with 韋, which likely contributes sound and may relate to enclosing or leather, but the exact historical development is uncertain.
The outer component 是 means 'right' or 'correct', and the inner 韋 looks like a wrapped package. Imagine checking that a wrapped gift is proper and appropriate before presenting it.
For イ, picture an easel (イーゼル) holding a sign that says 'This is the right way'. The 'e' sound in easel cues イ, and the sign points to what is proper.