Answer:
When set loose I fly away. Never so cursed as when I go astray.
What has to be broken before it can be used?
Metal or bone I may be, many teeth I have and always bared. Yet my bite harms no one. And ladies delight in my touch.
Always wax, yet always wane: I melt, succumbed to the flame. Lighting darkness, with fate unblest, I soon devolve to shapeless mess.
At night I come without being fetched. By day I am lost without being stolen.
My days are numbered. What am I?