final particle expressing consent, talkative
呭 centers on speech that flows freely: being talkative or expressing consent with a final particle. The two meanings connect through the idea of easy, agreeable verbal expression.
呭 combines 口 (mouth) with 世, which likely contributes the sound. The exact historical development is uncertain, but the structure suggests a phono-semantic compound related to speech.
A mouth 口 beside the world 世: imagine someone talking about the whole world, never running out of things to say. That talkative mouth easily agrees with everything.
For エイ, picture a talkative person saying 'A' (エイ) as they start every sentence, like a drawn-out 'ehhh' sound before launching into chatter.