Star Metal Bolts

Description
"Conan bounded back from the waving bills and his leap carried him outside the ring of his foes, to where Arus stood fumbling at his crossbow. A savage kick in the belly dropped him, green faced and gagging, and Conan's sandalled heel crunched square in the watchman's mouth."

- The God in the Bowl

Without bolts, a crossbow is just a really poorly shaped club.

Bolts of start metal pass through armor like a heated knife through tallow.

Star metal is rare, smelted from ore that falls from the heavens. Weapons made from such material are preternaturally powerful.