Blade Steal

Blade Steal is the martial art technique Ikki Kurogane created and derived from his Perfect Vision.

Description
"Swordsmanship describes its own knowledge, style describes its own history, and breathing describes its own principle. If one followed the branches and leaves of a sword style and arrived down at the root, then it wouldn't be hard to grasp that style's techniques and combinations, or its approach in facing different situations. This was what Ikki was saying."

- The description of Blade Steal

Blade Steal is a technique that is derived from his Perfect Vision, where Ikki uses his incredible insight to analyze and steal another opponent's swordsmanship or technique through tracing them back down to their roots. He can grasp most forms in a couple of minutes to discover their imperfections and seconds to create a far more superior version of it, which he applies to his swordsmanship. The true strength of Blade Steal comes when he was able to trace down the roots of the Ayatsuji Ittou-ryuu through practicing with Ayase Ayatsuji then reproduced their secret technique, Ten'i Muhou despite not seeing her perform it once.

It was used for the first time against Stella Vermillion after "stealing" her Imperial Sword Style, taking two minutes to steal it and thirty seconds to surpass it. This could be used on techniques that aren't swordsmanship based as first shown after seeing Touka Toudou using Trackless Step.

Weaknesses
Although, Blade Steal is a powerful technique, which grants Ikki an advantage in a fight against Blazers who uses martial arts. It can take him a long time to analyze, steal, and perfect the specific swordsmanship that he is trying to replicate when that person has honed it to an incredible extent as first shown as he "stole" the Imperial Sword Style of Stella. This is further elaborated as he couldn't use Edelweiss' Swordsmanship to the same level as the Strongest Swordsman due to the wide difference in their skill as swordsmen since Ikki produced too much noise.

Known Copied Styles and Techniques

 * Kyokujitsu Isshin-ryuu: Ouma Kurogane
 * Yagyū Shinkage-ryū (Mutou Dori)
 * Yuuri's Swordsmanship: Yuuri Oreki
 * Imperial Sword Style: Stella Vermillion
 * Ayatsuji Ittou-ryuu (Ten'i Muhou): Ayase Ayatsuji
 * Trackless Step: Touka Toudou
 * Edelweiss' Swordsmanship: Edelweiss

Trivia

 * Ikki is mentioned having learned 126 sword styles in total as revealed in Light Novel Volume Zero.
 * Ten'i Muhou and Edelweiss' Swordsmanship are the two techniques that Ikki hasn't made a superior version of, with the latter being more adapted to suit himself.