Angels, much like their demonic counterparts, have four forms they can take thanks to the imagination of their mortal believers.
Human-form: Self explanatory.
Within this form, they have a natural beauty about them. They radiant warmth and comforting aura whether it be false or not. Humans will feel a natural attraction towards them may it be sexual or not.
Demi-form: Almost like what mortals believe angels look like, an angel's demi-form is very much human-like.
Depending on their rank, every angel has a pair of head wings that cover their eyes if they are not glamoured.
The higher the angel's rank, the more head wings they'll have. The most is a total of four wings.
† - The insides of their wings contain two pairs of eyes that they are willing to flash at you.
† - If one gazes upon an angel's eyes will see things a mortal must not see at the cost of their sanity. The mortal's eyes will boil and burn and death will follow suit.
✸ - And yes, angels are equipped with a pair of wings at their back. However, this also depends on their rank. An angel may have up to six and may glamour as many as they wish.
Animal-form: Angels will often take form of avians (birds). Again, this is due to the beliefs of mortal beings.
True-form: A form mortal minds cannot comprehend. They are not beautiful as depicted in fine arts. Much like their counterparts, they are eldritch horrors themselves.
† - Like above, if an angel shows their true-form to a mortal, they will instantly combust into flames.
Angels contain the blood of their creator: God. Their blood is metallic gold in hue and runs hot. Hot enough to burn whatever surface their ichor manages to touch.
† - Their tears also share the same properties.
Before mortals existed, those found within Heaven were gender-less. This also includes the existence of God.
However, when mortals began to have thoughts and beliefs of their own, their ideals of Heaven were very different from actual reality of it.
The more humans believed to put gender labels upon those above the clouds, those within Heaven adapted. Angels took shape of forms they were believed to have which are mostly male.
† - Some individuals are Androgynous.
† - With modern times, female angels have been known to exist however, extremely rare.
During certain times of the year (and much like any male avian), an angel's wings change in colour to attract mortal mates and or for more territorial displays within layers of Heaven.
† - Outside of this above, the color of an angel's wings is based off the bird species they've adapted to their identity. Their wings are not pure white like common mortal beliefs.
† - Angels are known to mix wings of butterfly or moth species with their feathers.
Physical halos do not exist. They have an aura behind their head called parhelion.
† - Only nephilim (angel/human hybrid) may have a physical halo if they prove themselves worthy enough by the Creator. This mainly acts like a dog tag.
† - Nephalem (angel leaning [demon/angel hybrid]) can also have a halo, but it is mainly a small amount of manifested energy.
† - Headcanons are sure to be added and changed.