This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
蠒 is a variant or older form of 繭 (cocoon). It combines 虫 (insect) with 爾, which may have contributed sound or served as a phonetic marker, but the exact historical development is uncertain.
The bottom 虫 suggests an insect, and the top 爾 looks like a complex woven structure. Picture a silkworm inside a tightly wrapped cocoon.
For ケン, imagine a silkworm spinning a cocoon that looks like a tiny tent: tent -> ケン, and the worm is inside.