The context of angels, demons, and Mary that you are using appears to be a Christian one, which isn't inherently compatible with (Neo)Wicca unless you were going the route of Christian Wicca (and even then, it tends to be Christianity with Wiccan flavoring as the Lord and Lady are viewed as aspects of the Abrahamic God or are eschewed entirely).
The little floaters you're talking about have been seen by people who typically attribute them to being ghosts, which is why they show up in more "Ghost Hunting" mentalities or as local attractions that are treated as "woo woo, oh so mystical"; anyone can catch these floaters on camera and not see them with their naked eye, but still have the hairs on the backs of their necks stand on end. Currently I don't think anyone knows what they really are (that I've seen).
In my experience, spirits aren't physical beings, so they shouldn't provide a form that can be physically seen - though through circumstance, their energy can "align" with physical happenings enough to appear as if they are manifesting physically. It's like seeing a dancing spirit in flames; physically speaking, you know they are just flames, but you can also get the idea that there is more presence than just the flame in a spiritual sense. Get what I mean?