Varos named the daggers himself, and used them in close quarters combat (switching to his magnum revolver, Highway Star when distance is between him and his enemy). The daggers were of master make, and were sharp enough that Varos only had to sharpen them once.
Varos was known to fight with a rather unorthrodox style when it came to his daggers; Starfang, in his right hand, was held in normal grip, while Vigilance, in his left, was held in reverse grip. This allowed Varos to perform a wider array of acrobatics while still slashing his enemy effectively.
Some time during the Cirsuimenian Invasion, Alex the Devilechidna took the two daggers and used her her earth powers to fuse them with an ornate metal rod, creating the double-bladed-staff Angel Star.