According to an official announcement on the COMIC METEOR website, after consulting with Broken Blade author Yunosuke Yoshinaga, the project has been cancelled.
Broken Blade was previously adapted into a 6-part animated film series in 2010 – 2011 with direction by Tetsurō Amino and Nobuyoshi Habara and animation by Production I.
The OAV was going to feature an original storyline that delved into the back-story of the Golem Delphine.