I've long been fascinated by angels, and believe they've been, and continue to be sent to intervene in both sweeping historical events and in the lives of ordinary people far more often than we might think.
While I don't give them the full force of Holy writ, two of the most credible contemporary stories of what might be described as angelic intervention involved characters with the appearance of a German shepherd and Jimi Hendrix. I suspect that angels take on the appearance of whatever God needs them to.
..and sometimes they are the very essence of God, as with the burning bush encounter.
Well Paul does give us warning to “take care lest ye entertain angels unaware”!