This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
玹 combines 王 (jade) with 玄, which likely contributes the sound. The exact historical development is uncertain.
The left side 王 suggests jade, and the right side 玄 is dark or mysterious. Picture a mysterious dark jade stone, but its exact meaning is uncertain.
For ケン, imagine Ken holding a piece of jade: Ken -> ケン, and the jade is the 王 component.