This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
碨 combines 石 (stone) with 畏, which likely contributes the sound. The exact historical development is uncertain.
The stone radical 石 suggests something related to rocks or minerals, but the overall meaning is uncertain. Picture a mysterious stone tablet with the 畏 component carved into it.
For ワイ, imagine a wise old stone (石) whispering 'why' (ワイ) in a forgotten language.
—