Kings are meant to be men of wealth, power and influence, who stood tall with pomp and circumstance. They also tended to have a great deal of regalia that went beyond the obligatory crown and fine garments. That’s why a lot of kings carried scepters like this blue one to display their might and opulence. It’s the perfect prop to bring your royal blue costume together.
If you ask a passionate cosplayer, they will tell you that it’s the right accessories that truly make the costume. That’s probably why you see so many king, queen, and noble costumes adorned with a royal blue scepter like this one. It’s perfect for renaissance festivals and medieval fairs of all kinds.