Ajax

Ajax, is a tool wield by the Sigma's legendary Susanoo. The shield grants Sigma's Susanoo the ability to absorb, not only any technique, but use the technique to his own extent. It also works as a functions, to absorbs the souls of the opponents, otherwise known as sealing them away. Sigma commonly refers to the shield as the "Hero Shield" — the only shield he ever used capable of saving him. After Sigma's death, Shirou, managed to get his hands on the weapon, by unknown means.

Trivia

 * Sigma calls the shield a hero, ironic because the shield if taken from 's hero.