I usually see the characters like Ed as ukes and characters like Roy, Hughes and Scar as semes. I think Envy could be either way :) Also I guess Ed is actually quite tough, which could be why it is a little hard to see him as an uke^^
Totally see him as a uke, just because he is a uke - does not make him submissive, he is a tsundere uke, temper and all. Plus, his eyes are always so big (typical uke sign, and in this one he is smaller - another sign)
i seriously can't see Ed as the uke. with his hyperactive short temper i just can't see it.