brief note, official communique
劄 centers on a short, official written message: a brief note or communique used in formal contexts.
劄 combines 答 (answer, reply) with 刂 (knife), suggesting a written reply that is cut or carved, perhaps originally on bamboo slips. The exact historical development is uncertain.
The left side 答 means answer, and the right side 刂 is a knife. Imagine carving a brief answer onto a bamboo slip with a knife to create an official note.
For サツ, picture a samurai (サムライ) quickly carving a brief note with his knife: the 'sa' from samurai cues サツ, and the knife 刂 reinforces the cutting action.