The Angels (天闘士, Enjeru) are the chosen warriors of the Olympian Gods. Their armors are named Glories (天 衣, Gurōrī). They are also some of most powerful foes Athena's Bronze Saints have ever faced not counting the Gods. The Cloths of Seiya, Shiryu and Hyoga are all more or less destroyed in their respective battles against the Angels during Tenkai-hen Jōso movie, despite being the most powerful Cloths, those reborn with Athena's blood. They appear also in Next Dimension manga, but only Toma has appeared so far, but he wears the Sleep Angel Glory instead of the Icarus Glory. Masami Kurumada talked about Angels in an interview where he was asked details on the possible Heaven Chapter and he said to have in mind to create warriors that may have been even stronger than the 3 Judges of Hell to make them fight against the Bronze Saints after the Hades Chapter that have gotten a lot stronger awakening the Eighth Sense, and they would have been the Angels. After the appearance in Tenkai-hen Jōso, he officially included Toma in Saint Seiya: The Next Dimension.
There is no information on the training of these warriors. However, seeing as they are at an higher level than a Gold Saint and possibly even higher than the 3 Judges of Hell, their training must have been intense, unless they may have climbed the divine ranks during past battles or some of them may have been born divine already.