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You are right: the 4 corners depict the 4 archangels or, rather, the symbols associated with them. But, being an agnostic myself, I am out of my depth here and cannot give you their names.
For me, the meaning of this card is the completion of a cycle within the bigger cycle that comprises our lifespan. Something like having mastered the challenges of one of the major arcana stages before tackling the next, although I believe we go back to each of them time after time and learn each from a different perspective.
In this sense, the 4 figures might be benignly supervising our efforts and celebrating our triumphs with us, so to speak. Since I am not religious, to me it is our inner serene self watching our growing process and making us feel good about our success in order to keep us motivated.
She -although many decks describe the figure as hermaphrodite- is holding a couple of wands just like the Magician's. In his case it might be pointing at his potential to do things, while in the World's they could be picturing proven abilities. Just a thought, though :smt002