To have this surgery I mean," Roy said softly, letting his fingers move around the brace and downward to the edge of the port that was just under his arm. Easy to anger, slow to trust. She got even harder in her actions as the night progressed. Is that the 'magic' that Havoc moans over? Similarly, why couldn't you kill someone by touching them and messing with their elemental structure?
It was with no small smug satisfaction to hear Ed make a small beseeching noise when Roy pushed off the bed and lifted one hand in Roy's direction.
That would make more sense, in my opinion. Involving Ed just seems like needlessly throwing a wrench into their plan. Ed curled when the warmth left him, watching Roy's back, noting with a little irritability that the Colonel still had on his pants. Technically, Scar is stopping at the deconstruction step of alchemy without actually reconstructing the elements into something else. I suppose that Ed could make his skin into diamond, but to do so he would have to pull that carbon away from, say, his bones and his organs and his brain and stuff. Lust regenerates an entire dress after being exploded multiple times, but I'm pretty sure she was wearing a different outfit when she was talking to Havoc as "Solaris," so I doubt it's a part of her body.