What he was encouraging, then, is that we need to hold all authority in question. We need to be suspicious, or at least discerning, of authority. The very things that claim and we presume are good for us may not be. Just because something comes packaged in authority, leadership, power, and control, it doesn’t necessarily mean it’s true. Angels may be devils!
So, for me, the metaphorical Angel of Light may look like authority structures, powerful figures, charismatic leadership, moving speech, appealing ideas, and contagious movements. This is not to say that the message content of these things is necessarily false and deceitful, but that they very well could be and perhaps likely are.
Discernment is job one.