The Name can be claimed or granted, and is one of the potential options for the Squire to transition into.
Amadeus himself transitioned into the Name from the Squire, while Marshal Nim was granted the Name and position by Dread Empress Malicia.
Catherine was considered a potential claimant for the Name, being groomed by Amadeus as his successor back when she was the Squire, but in the end, deviated too much from the Role to claim it.
It was held by Amadeus of the Green Stretch for nearly forty years by the start of the story, with him finally losing the Name in late Book 4.
The Black Knight is the right hand of a Dread Emperor or Empress. Their martial champion, with the traditional role as a breaker of heroes.
It is noted that previous Black Knight, Amadeus was out of sync with the Role of his Name, as he preferred leading the Legions of Terror and ruling as King of Callow in all but name, causing him to be far weaker than a traditional Black Knight.
By contrast, his successor Nim Mardottir had the Role of ‘General of the Empire’s Armies’, showing that by the time she claimed the mantle some forty-five to fifty years later, Amadeus had carved the Role of being a military commander into the Name.
The Black Knight has abilities revolving around the commanding of armies. Amadeus had the aspects of Lead and Conquer, which were capable of empowering the soldiers under his banner. While Nim had the aspects Delegate and Survey, allowing her to fight on the frontlines while simultaneously commanding from the rear.
The Black Knight has the ability to control undead, just like the Squire, though the number of undead the Black Knight can control are considerably greater. It also allows the user to manipulate their shadow, fashioning weapons or even using the shadows as extra limbs to carry crossbows in battle.
The Black Knight can also Speak, Amadeus in particular being an extremely skilled Speaker. Far better than any Black Knight had the right to be.
Amadeus could use the Speak to enemy soldiers, turning them into hidden assassins with five implanted orders. One to wipe the memory. One trigger. One act. Two contingencies. In Delos, Amadeus was able to suborn around a dozen Delosi officers into attempting to assassinate the White Knight and his band, and when they failed, commit suicide. The survivor had no memory of the incident.
This formula was known to the heroes, suggesting that it wasn’t the first time that heroes had dealt with a Speaker villain, potentially another Black Knight, that used it.
Like any martial Name, it grants the user great strength, reflexes and a near-guarantee of winning all but the most massive battles against non-Named. Moreso than the Squire. Amadeus mentions that his predecessor had the ability to topple a tower with a wave of his hand, but eventually died by getting stabbed in the throat by a foot soldier.
Amadeus and Nim both demonstrate enhanced reflexes and speed when in combat, with Nim being able to bat aside arrows shot by Archer even when in a smoky battlefield or when being thrown into the air by Catherine.
The aspect Conquer is a staple of Black Knights, presumably due to their job as the foremost champion of the Dread Empire. A nation whose main objective over its 1300 years of history was the conquest of the neighbouring Kingdom of Callow.
Amadeus mentions that Conquer allows a Black Knight to draw out more of their Name’s power when conquering something. Making it a popular line of thought among the Black Knights of past to be constantly conquering. But he also warns that the amount of power accessible isn’t infinite, and leaning too much into Conquer could lead to tunnel vision.
In Amadeus’ case, Conquer empowered his reflexes slightly in a fight, but it’s main use was the empowerment of soldiers. In stark contrast to his predecessors, who’s aspects tended to take the shape for the killing of heroes, instead of the leading of armies.