This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
賆 combines 貝 (shell, money) with 并. The exact historical development is uncertain, and the character is rare with no clear established etymology.
Since the meaning is unclear, focus on the shape: 貝 (shell, money) beside 并. Imagine a rare coin with the 并 pattern on it, but its value is unknown.
For ヘン, picture a hen pecking at a shell (貝) next to a strange 并 shape: hen -> ヘン, and the hen is confused by the rare coin.