Short promotional animation clip was released as part of a special Comic Blade Digital DVD sold at Animate.
Based on a manga "Erementar Gerad: Aozora no Senki" by Azuma Mayumi serialised in Comic Blade Masamune and later in Comic Blade Avarus starting on September 15, 2007. It is a spin-off of the mangaka's earlier series Elemental Gelade.
(Source: AniDB)