User blog comment:Shadow-Flare/ShadowForge Inc./@comment-5136106-20120130200420/@comment-2116776-20120130211654

they are transformed demons/celestials/spirits which allow the person who defeated them to control the element or attribute the weapon is alligned to as well as another ability which are listed on The Twelve Demon/Celestial/Spirit Weapons pages. they can change into they're true forms if allowed to by the owner and the weapons can be summoned and dismissed at the owner will (I.e. Diablos' weapon form can be pulled from a black hole)