Bound by adamant chains

When God designed the Angels, he intended them be nearly perfect servitors, skilled at a number of different tasks and to each angel he gave a Caste which gives that angel dominion, control, and influence over certain types of activities or concepts. Whereas the graces are intended to serve as a core of power determining what kind of affinities the angel has, the Castes are what makes an angel, an angel. Each Caste was given different functions and purposes.

Archangels

These primordial beings are the first angels to have been created. As such Archangels are given dominion over all other angels and nearly the entire cosmos as a result of that grant of power. Michael, the first angel is an Archangel, as is Lucifer. Archangels are by far the most powerful beings that currently roam the earth at large, and should not be trifled with lightly.

Archangels are administrators and generals, but also living weapons and are considered to be "Heaven's most terrifying weapon". How many Archangels there are is an unknown, and it is believed by the other angels that every so often God creates a new archangel, just to remind his Children that he still lives. Archangels view themselves as the highest authority over all of creation since God's departure from Heaven.

Appearance & Features: Like all angels, their true forms are very intense, and have proven not only harmful but also fatal to humans, though Castiel also claimed that special humans can see their true forms. Their presence on Earth outside a vessel is often visualized as a blinding, pure white light, and their arrival can cause minor tremors. Their true voice also emits a piercing sound, which has proven to be excruciatingly painful to humans. Even in Heaven, the Archangels generally appear as pure light of various colors.

Leadership: Michael, Prince of All Angels and Voice of God

Grigori

The Watchers are observers and cataloguers of sins or virtues, potent angels who observe their fellow angels, ensuring that the other angels are obeying orders and following instructions. After the creation of humanity, the Grigori have also been tasked with observing and watching humanity with the result being that many Grigori are incredibly fond of humanity and are some of humanity's most ardent defenders. Their powers allow them to interact with humans more easily than other angels, also allowing them to manipulate humanity.

Appearance and Features - The true form of the Grigori is that of a being with multiple faces which look in all directions and multiple sets of wings.

Leadership: Raphael & Gabriel

Praelia

The Vindicators are angels whose purpose is war, battle, and the protection of the weak and innocent. Representing both the worst and the best in warriors, soldiers, and guardians, the Praelia are often Seraphim. Although all angels are expected to be warriors at need, the Vindicators are the Caste of angels whose whole purpose is the glory of battle and to ensure the triumph of Heaven over any and all adversaries. Vindicator’s lore, both modern and ancient, are sometimes referred to as Valkyrie.

Appearance and Features - Praelia are the most human looking angels when in their true visage, and typically have on armor which shines as gold, silver, and steel, and carry a small army's worth of weapons on them. They have four arms and four wings and their eyes devour and challenge.

Leadership: Camael & Cassiel

Custos

The Wardens are angels which are charged with the guardianship of the individual heavens of worthy humans, but are also tasked with the internal policing of their fellow angels. Acting as investigators, trackers, and police, the wardens are the angels dispatched when demons are wreaking havoc and need to be contained rather than fought directly. They are also the type of angel most likely to be encountered by other supernatural creatures, often to the sorrow of those creatures. Unlike the Vindicators, the Wardens do not consider their primary purpose to fight, but they are not slouches either if provoked to violence.

Appearance and Features - The Custos appear as four interlocking wheels of fire, with each wheel bearing numerous eyes which stare unblinkingly at the world around them and each wheel bears a set of fiery wings.

Leadership: Kushiel & Uriel

Naturae

The natural world, the governance of the animal and plant kingdoms, are under the jurisdiction of the Rabisu, angels of nature who wield the power over nature in all of Her wild forms. Oftentimes considered to be savage, if there is a quality of beasts, then there is an angel who created, designed, or implemented that quality. The Rabisu generally do not greatly care for humanity, believing that humanity has defiled the world they helped create and build. With the gates of Heaven open and the angels descending, it remains to be seen if they will use their power for destructive or creative purposes.

Appearance and Features - In their true form, the Naturae take on a form that blends animals and humans, or plants and humans, or all three. They could have the legs of a man and their body be that of a squid or covered in blooming flowers. They do not appear to have wings unless they wish to.

Leadership: Sammael & Metatron

A Note About True Forms

Angels, to human senses will typically appear as nothing but radiant light. The intensity of that light, however, can change with stronger angels able to burn the eyes out of people that try to see their true forms. Almost all angels can dampen this effect, and reveal themselves in glory and power as Angels of the Lord and show forth their true form.