This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
玽 combines 王 (jade) with 句, which likely contributes the sound. The exact historical development is uncertain.
The left side is 王 (jade), and the right side is 句 (phrase). Picture a phrase carved into a piece of jade, but the meaning remains mysterious.
For コウ, imagine a jade craftsman named Kou carving a phrase into the stone: Kou -> コウ.