to beat, to strike
撾 centers on forceful physical impact: beating or striking something with a hand-held object.
撾 combines 扌 (hand) with 過, which likely contributes the sound. The character is rare and its exact historical development is uncertain.
The hand radical 扌 beside 過 suggests a hand moving past something with force, like a hand striking as it passes by.
For タ, imagine a hand striking a drum with a sharp 'ta!' sound: ta -> タ, and the hand beats the drum.