This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
詶 combines 言 (speech) with 州, which likely contributes the sound. The exact historical development is uncertain.
With 言 (speech) and 州 (sandbank), imagine words flowing like a river around a sandbank—perhaps a curse or a chant, but the meaning is uncertain.
For シュウ, picture a shoe (シュー) being cursed with words: shoe -> シュウ, and the speech radical 言 delivers the curse.