Why is the ninth month called September?
c.1300, ceptre, from Old French sceptre (12c.), from Latin sceptrum "royal staff," from Greek skeptron "staff to lean on; royal scepter;" in transferred use, "royalty," from root of skeptein "to prop or stay, lean on." Apparently a cognate with Old English sceaft (see shaft (n.1)). The verb meaning "to furnish with a scepter" is from 1520s.
ornamented rod or staff borne by rulers on ceremonial occasions as an emblem of authority and sovereignty. The primeval symbol of the staff was familiar to the Greeks and Romans and to the Germanic tribes in various forms (baculus, "long staff"; sceptrum, "short staff") and had various significances. The staff of command belonged to God as well as to the earthly ruler; there were the old man's staff, the messenger's wand, the shepherd's crook, and, derived from it, the bishop's, and so on.