User blog comment:B214/Light Novel Volume 16 spoilers/@comment-82.40.154.8-20131227171125/@comment-1359322-20131227171558

Aside from the Top-tier Longinus being said to be able to destroy the world, none of the exact power of the Longinus are stated. The only reason why they are Longinus is because those Sacred Gears have the abilities to kill God.