The Wulfenbach Stealth Fighters are first seen at the Siege of Mechanicsburg, attacking the downed airship of the defecting Vespiary Squad. They wear black uniforms with red facings, a hoodlike hat, and asymmetrical red goggles. These, along with the owl wings on their cap badges, suggest that they normally fight under cover of darkness. While they do carry pistols, the ones seen at the Siege chiefly used poisoned blades.
The bulk of the unit shown dropped into a landing zone full of Jägergenerals, who promptly massacred them, with Khrizhan shooting down their airships for good measure. Several managed to invade the wreckage of the Vespiary ship and cause trouble, notably the one who backstabbed Ruxala with a poisoned blade before Tarvek killed him and his partner.
The use of this unit to pursue the Vespiaries and their precious Wasp eaters, rather than a less specialized one better suited to the task, and the restrictive Rules of Engagement they fight under might be the result of Klaus' campaign of Inefficient Obedience against Lu'nevka.