Wallenstein

"There is only one rule governing this world. The strong take, the weak are taken from."

- Wallenstein

Wallenstein, also known as the One-Armed Swordsman, was one of the Numbers for the terrorist organization Rebellion and the former mentor of Nagi. After somehow surviving his fight with Shizuku Kurogane, he later fought against Or-Gaule, but was soon killed by Naseem Al-Salem.

Appearance
Wallenstein was a middle-aged man. He had short grey hair and scars over one of his eyes, as well as a missing left arm. He usually wore a black robe.

Personality
A very hardened individual, Wallenstein believed that there was no love in the world and that anyone who thought there was such was foolish.

Wallenstein has shown to be a very cruel individual wanting to punish Nagi before killing him, by killing the very person Nagi has taken to as his sister. Wallenstein was also a sociopath as he took lives without much remorse or care. Wallenstein also seemed to have an important position in Rebellion, having trained many of its assassins.

History
At some point, Wallenstein brought Or-Gaule to join Rebellion, in order to help their cause.

Sometime later, Wallenstein was hired by the mayor of the town Nagi was living in as an orphan with the nun and the other children. After Nagi killed all the gang members for killing his close friend, Yuuri, and captured the other orphans, the gang who Wallenstein was tasked to "clean up". After introducing himself to him, he gives Nagi the severed head of the mayor. He later persuaded Nagi to join Rebellion, but only after Wallenstein had paid Nagi one-hundred million dollars. Under Wallenstein's tutelage, Nagi becomes a merciless assassin, killing any person Wallenstein had asked him to kill.

Training Camp and Scheme
Wallenstein talks with Nagi on the phone, during the training camp, after Nagi has called Reisen Hiraga. He asks if Nagi is ready for his role to betray the Hagun students that he has pretended to be a friend of for months. Nagi answers positively, which pleases Wallenstein, who believes Nagi to be the greatest student he has had.

Akatsuki Strikes
Wallenstein is first formally seen at Akatsuki academy, when he began to interrogate on the reasons why Nagi would betray him. After learning Nagi's reasoning was because he cared about someone, Wallenstein became angered and then decided to punish Nagi before killing him, by killing the very person he cared for the most, Shizuku, who had just arrived.

Wallenstein was able to overpower Shizuku during his fight with her, being able to nullify all of her attacks, due to his friction manipulation ability. Wallenstein seemingly kills Shizuku, but Shizuku manages to survive by turning her own body into vapor with Aoiro Rinne. Wallenstein is defeated by Shizuku, the very air Wallenstein was breathing to drown him. Wallenstein survived the encounter and escaped through unknown means, returning to Rebellion's headquarters.

A Night of Massacre
During Or-Gaule's attack against Rebellion's headquarters, Wallenstein encounters Or-Gaule himself, intending on killing him. Or-Gaule though is not intimidated by him, mocking Wallenstein for losing to a B-Rank student knight. Wallenstein however, manages to cut down Or-Gaule's Deus Ex Machina and almost defeated him, only to be killed himself by Naseem Al-Salem. It is implied that Or-Gaule didn't take the fight seriously, having only been playing around.

Abilities
Friction Manipulation: Wallenstein ability as a Blazer. With this ability, he was able to nullify all physical attacks and steadily walk on ice without much problem.
 * Attack Nullification: By lowering friction, Wallenstein could nullify the power of any physical attack, making him basically invincible.
 * Attack Enhancement: By increasing friction, Wallenstein could greatly increase the power of his attacks.

Master Swordsmanship: Wallenstein was regarded as one of the strongest swordsmen within Rebellion, despite him having one arm. Nagi also held his sword skills in high regard as he didn't want Shizuku to fight him. He was even able to engage Or-Gaule who is a desperado and almost killed him albeit, the latter wasn't even serious and was just playing around.

Immense Endurance: Wallenstein has proven himself to be able to survive being pierced from inside by Shizuku ice spikes somehow and was also survive some time after his heart was torn out by Naseem.

Expert Assassin: Wallenstein was a skilled assassin, having taught Nagi and being one of Rebellion's strongest members.

Device
Unnamed Sword: Wallenstein was shown to have a very large sword as his Device, which he could overpower many foes with, without much effort.
 * Bergschneiden (山斬り, lit. Mountain Cutter): A deadly cutting attack used by Wallenstein. It was strong enough to cut through Or-Gaule's Deus Ex Machina and the mountain behind it. Wallenstein used friction to increase the technique's power.

Trivia

 * Wallenstein is likely from Germany, due to both his name and Noble Art.
 * Wallenstein had his left arm when he first encountered Or-Gaule, meaning that he lost it soon after meeting him.