British royal Rod of Equity and Mercy, e.g.

SCEPTRE

This ceremonial staff, often topped with a jewel or orb, symbolizes a monarch's authority and is commonly seen during coronations. Think of a word that starts like "science" but ends with royal power.

This clue refers to the ceremonial staff carried by British monarchs during coronations, symbolizing their authority. "Rod of Equity and Mercy" is a poetic way to describe a scepter, which is often associated with justice and power in royal traditions. The word "e.g." hints that "SCEPTRE" is just one example of such a royal rod, making it the straightforward answer. British spelling ("SCEPTRE" instead of "scepter") confirms the answer fits the clue perfectly.