Angels, as have been touched on before, are the umbrella category for any beings created by a god or gods for a particular task. It’s a broad term, but then being celestial is a broad implication. Some angels might even conflict with others, depending on the purposes they are designed for. Angels of death, for example, run counter to angels of protection.
Flying Sea Serpents are actually angels. Created by Cora, the goddess of water, and Sil, the goddess of air, their divine purpose is simple. They guard the sea and sky wherever they are placed. Their original purpose was to guard the shores of Muunfel, but many have been slain and their numbers are reduced.
Some gods are less likely than others to create angels. Others simply aren’t sure what to do with them. Wiavex, the god of souls, for example, has created one angel, unique in its shape, which has a very clouded purpose. It is simply a Soulgazer Beast, consigned to see the souls of mortals with no task to complete with the information it finds.