Ed’s arm in episode 51 while he’s in Munich is not the same AutoMail Winry gave him. It’s a much more low quality one. It’s ability (or lack their of) was shown to us a few times by how rigid his arm is as he packs his suitcase (Ed would never have been so stiff had he had a proper AutoMail). I believe Ed has partial to substantial range of motion for his shoulder, elbow and wrist.  I'm going with poor to no movement of his fingers and only partial movement of his thumb (from how he was holding the paper). If you look closely at all of the times they show the feeble AutoMail, Ed’s fingers never bend or separate. That’s how I’m writing it; writers prose ^_^. The final image of Ed reaching for the sun with the AutoMail arm is simply symbolism; that’s not the actual arm he has. Ed is still searching to reclaim what he’d lost, one of those things now being an AutoMail like the one he’d had before.

This is the type of Auto-Mail I will depict in the story (right or wrong, we'll all know for certain August 2005).