Assume that space warfare is dominated by gamma and x-ray lasers (Wakefield-Plasma and Free Electron Lasers) capable of killing targets several light-seconds away. Stealth in space is possible due to optical metamaterials and cooling tech, this is a set assumption. However stealth is rendered useless by x-ray phosphorescent scanning. Antimatter mass-production and fusion are well understood technologies and are easy to use. The setting is nonetheless supposed to be hard-scifi.
While conventional projectiles will be vaporised quickly by the lasers, and throwing kilometer sized asteroids at them to overwhelm them isn't really an option, a black hole would be a projectile utterly immune to laser fire. Ultra small Kugelblitz black holes with lifetimes in the days or hours seem to be suited best for this, due to their relatively low mass and the fact that they will give off enormous amounts of energy as gamma radiation. Scale the black holes right and even a near miss can evaporate an enemy spacecraft. The only way to counter this would be evasion or point-defense with defensive black holes, which perform a flyby maneuver to deflect the incoming black hole.
The Kugelblitze are generated using the laserstars laser and mirror essemblies, either tuned down to lower wavelengths or using x-ray mirrors. Basically the mechanism just puts enough photons in one place to create a black hole of the desired mass.
The issues begin after the Kugelblitz is generated. How do I move a Kugelblitz black hole? I know that gravity, meaning a gravity tractor, would work, but the performance would be pityful. Can the black hole be manipulated by electro-magnetic fields? If that where the case, would building a coil-gun or a missile out of it be possible?