He frowned in thought as she explained, mildly horrified by the idea of being pulled apart and put back together everytime so traveled. If Shadow-Walking was like that, or painful, which he assumed it wasn't , he imagined he would never do it.
The Kartaians would, but they were sadistic bastards. 

"Yes." He said briskly. "I can't feel my hands." He shrugged his shoulders, as his hands were stuff back into his pockets, balled into fists. And while the majority of his face was covered once more, his eyes were watering from the chilly wind.
At the very least, his feet were warm, stuffed into the non-small boots.

"Shadow-walking," Ruli began, figuring he could explain in exchange. "is uh." Fuck. Envy always explained it better. "Shadows are connected. They're all the same. Its using a sort of back door to an in-between realm to step from one to another. When I do it, it doesn't take much energy, but a lot of focus, and strength. Not quite the same as yours. I am physically dragging you or whatever I am holding along. The heavier the burden, the harder it is. Like trying to sprint uphill."