It's the process by which an angel converts energy into action that Balthazar can't explain. It's such an instinctive part of him. Perhaps it's like a bird trying to teach a human to use a hang-glider. The principles of flight are the same, but 'you just use your wings!' isn't an effective way to explain how air currents are caught and ridden through the ether.

Something's happening, though, clearly, because he feels a faint twinge in his arm. The blood flow from the wound seems to be slowing gradually, but more importantly the skin under his fingernails is starting to go bluish-violet.

"Well...that's a start. Not very comfortable." But he's willing to take it a moment longer, if it helps the learning process.