This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
挩 combines 扌 (hand) with 兌, but the exact historical development and original meaning are uncertain.
The hand radical 扌 beside 兌 suggests an action, but without a clear meaning, picture a hand doing something vague with an object shaped like 兌.
For タツ, imagine a hand reaching out to touch a tatsu (dragon) statue: tatsu -> タツ, and the hand touches the mythical creature.