An orion is a metal throwing star, similar to a Japanese shuriken, which was developed by Nilfgaard. They are small and easy to conceal, but accurate and lethal from up to thirty feet away. When thrown, they also make a whistling noise which is said to paralyse potential targets with fear.
Codringher got a hold of some and practices with them for a while, he rather liked them. They were also a weapon of choice for Stefan Skellen.