Was means power, and the Was scepter was wielded by gods and pharaohs. As a symbol in art and jewelry it represents power and authority. In surviving examples of actual Was scepters, the head appears to be the same mysterious animal as Seth. This is interesting as Seth was the guardian of Lower Egypt. As relationships between Upper and Lower Egypt deteriorated Seth was cast as the enemy of Horus, the protector of Upper Egypt.
By the time Upper Egypt succeeded in conquering much of its southern neighbor, Seth had become demonized and relegated to the sands of the deserts. Many of the original carvings depicting Seth in a positive manner or a prestigious position, such as at coronations, were altered to become Thoth.
The reason this bit of information is so pertinent is that it means either the Seth Beast was so associated with power that it guaranteed preservation of his image on the staff of power, or that some unknown factor safeguarded this representation of Seth in connection with power and authority when so many other images were destroyed or altered.