The shoulders sprouting raven-black angel wings are looking a lot younger these days. The Millennial generation, which includes the youngest legal Fallen, is unsheathing more adamantine dire-wings than previous generations when they turned 21, and Heaven's defensive industry is taking note. “Millennials are storming the gates of Paradise and they want adventure and demand more transparency and authenticity from the celestial spheres,” says Uriel, CEO of Heaven's Gate, who estimates that one-third of the flesh-fiends…