obviously a poetic allustion to oppening oneself to emotional intamacy, though no further context is suggested by those lines alone, without more of the context in which they themselves occur. =^^= .../\...
Armour falling down at my feet implies trusting enough to be more open. Winter giving way to warm would suggest they feel that things are becoming better, and in the context of the first stanza could mean heart becoming warmer. Romance.
Letting the wall built of fear crumble, opening up, finally feeling alive. I absolutely adore Fiona Apple, and Pale September is one of my favorite songs of hers.