This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
譓 combines 言 (speech) with 惠, which likely contributes the sound. The exact historical development is uncertain.
The left side is 言 (words) and the right side is 惠 (a shape associated with kindness or benefit). Picture words that are meant to be kind or beneficial, though the exact meaning is unclear.
For ケイ, imagine a kind person named Kay speaking gentle words: Kay -> ケイ, and the words 言 on the left carry her kindness.