Did Ed really infuse the armor with his brother's soul, or is it like The Slicer said where its only memories designed by Ed himself? I'm not saying that Ed did it on purpose, but maybe when he thought he was implanting Al's soul to the armor he was really just implanting memories onto it.
I was thinking it was similar to the humunculus. Their bodies were just created but they had no soul but they did have memories.
Also, since they humunculus have no souls, how come they can still move and everything? And how come when the sowing life alchemist made Nina with Al's philosopher, how come she didn't move like the humunculus who also don't have a soul?