What does it mean for a soldier to give an armband to his lover? What does a heavy brand mean?

Remember a lyric: there are half of me and half of you on the military medal; Give your beloved an armband to show her unique military feelings, so that when she sees this, she will think of a man who really loves herself in the hot military camp and needs her support and understanding when she is happy and sad. It is also a sustenance of missing!