His gaze drops at this question and he considers for a significant moment or two whether to tell the truth. Most of the truth should do in this instance. For some reason he feels that Zel might understand what he means without him having to spell out the details. "I lost the leg doing something I wasn't supposed to, and the arm to try to fix what I'd done." He pauses, then meets Zel's eyes. "Equivalent exchange."
These words give him pause as they seem significant coming from someone like Zel, even as little as Ed knows of him so far. He nods, his smile spreading to more parts of his face. At the final question he laughs ironically, covering his eyes with his metal hand. "I wouldn't know. I'm new here, remember? Does it matter?"