Abdiel is Hebrew for "Servant of God", Abdiel is a Seraph in the Sepher Raziel and Milton's Paradise Lost.
In Paradise Lost, Abdiel denounces Satan after hearing him incite revolt among the angles, and abandons Satan to bring the news of his defection to God. However, when he arrives, he finds that preparations are already underway for battle. In the ensuing fight, Abdiel smote Satan, Ariel, and Arioch, presumably among others.