scepter

1. A staff held by a sovereign as an emblem of authority.
2. Ruling power or authority; sovereignty.

[Middle English sceptre, from Old French, from Latin scēptrum, from Greek skēptron.]

n.

A king's staff of office, the sign and symbol of his authority. It was originally a mace with which the sovereign admonished his jester and vetoed ministerial measures by breaking the bones of their proponents.

The noun has 2 meanings:

Meaning #1: the imperial authority symbolized by a scepter
  Synonym: sceptre

Meaning #2: a ceremonial or emblematic staff
  Synonyms: sceptre, verge, wand