Raziel has given this lecture before, but more often to new angels than to a summoner. She calls up her standard summary in her head, editing it a little for her audience.
"Angels have the power to change any physical object, including ourselves and other people, into any other physical object with sufficiently similar mass and volume. 'Sufficiently similar' does not mean 'identical': I may change a small dense object into a larger less dense object should I choose. However, it is difficult to alter mass or volume by more than a single order of magnitude.
"The only hard limit is that an angel cannot make something she does not know how to make. If I attempt to change, say, a stone into a pocket-watch, I must have detailed knowledge of a pocket-watch's workings. Similarly, working on the human body requires knowledge of anatomy."
She stretches out one wing to the extent permitted by the circle. "I sculpted these wings myself, from a substance common in Heaven known as 'cloud-fluff'. The knowledge to do so was gained through months of study regarding birds' wings and the creations of other angels."