I know people like hearing more about how angels really "are," so whenever I think of something else to share, I try to mention it on this blog.
Science fiction characters have X-ray vision, and we all know about medical and security X-ray machines. So I thought that there is a way to make how angels view "the world and humans" using this analogy.
People know that light comes in a wide spectrum of wavelengths, and some cannot be seen by humans (such as "heat," people can't see the wavelengths that produce heat).
Well, angels can not only see everything there is to see in the material and energy world, but they also see the presence of the Holy Spirit. In other words, angels always can see where the Holy Spirit is moving, and where the Holy Spirit "indwells" in people in the form of grace. So that is why I make the little humorous analogy that angels have G-ray eyes and G-ray vision. They can see grace.
So Gabriel would have seen Mary shimmer, for lack of a better descriptive word, with the fullness and beauty of her God given grace. So when Gabriel called her "full of grace" as a title, he did not have to take God's word for it. Angels see with the fullness of vision that God sees, naturally, since angels are entirely of God's realm. And thus angels can "view" at any time the extent and work and presence of the Holy Spirit in the physical world, and where the Holy Spirit "indwells" in the form of grace.
And no, people cannot see grace. It is not "aura" or any other energy or material manifestation. Angels see God's work using the manifestation of God's will, which is not in a form that anything living can see or detect.
I thought that you might find this interesting to ponder, and a little more insight about the reality of angels.