Blade Steal

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

Description
Blade Steal is a technique that Ikki Kurogane had created, which lets him "steal" someone else's swordsmanship due to no one wanting to teach him anything. He is able to use his incredible insight to trace the roots of any style he sees, thus letting him grasp a styles techniques despite not seeing it performed in front of him as shown when he was able to use Ten'i Muhou through helping Ayase Ayatsuji improve her swordsmanship.

Through the use of Blade Steal, he is able to grasp ones' sword style in a couple of minutes as well as find their flaws, then Ikki is able to perfect them creating a superior version using his swordsmanship. He is able to steal styles that aren't sword techniques.

Weaknesses
Though Blade Steal is a strong technique, which grants Ikki an advantage in a fight, it can take a while for him to do so based on how much one has trained and honed them as shown when he stole the Imperial Sword Style of Stella. This weakness is further shown as despite him stealing Edelweiss' Swordsmanship, Ikki couldn't use it to the fullest since it still produces too much noise among other major differences from the two styles.

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-ryu (Ten'i Muhou): Ayase Ayatsuji
 * Edelweiss' Swordsmanship: Edelweiss

Trivia

 * Ikki is mentioned having learned 126 sword styles in total as revealed in Light Novel Volume Zero.