Angel is a position inside superior metaphyisical entities, being the lowest. However angel is used to denote all the superior metaphysical entities.

They play roles as messager or guardkeeper, they could be also scribes, warriors and councelors. As superior methaphysical entities they can't directly interact with physical dimension, using vessels or prophets to reveal their thoughts. 

Through their vessels they can manipulate the weather and energy in different ways creating flames, sparks, earthquakes etc. They are also able to heal or destroy many of physical entities with a very little effort. Vessels can move as faster as a military airplane and are invulnerable of many kinds of damge.

Despite angels are immortals, they're not invulnerable, they can be knock out by some weapons. They're also sensible to forced obediences from physical entitites, despite no human has been ever able to do that (just with fallen angels )