Along with a handgun called Seven-Shots, BRS Blade is a sword (one of two new weapons) carried by Black★Rock Shooter Beast. It is much larger than Black Blade, BRS's traditional blade. The sword's blade is transparent with a black hue. The sword seems to have some sort of computer that shows some warning signs and when the blade is about to activate.
BRS Blade is only seen as a concept in the BLK artbook and BRSB's figma. Huke has no other artwork of BRSB using the BRS Blade.