Thus begins the rise of Unblinking's threadomancy!
It was an okay story, but had a lot of problems. My favorite part was the odd fact that the dragon was old and frail and probably had been for centuries but nobody realizes it.
A few of the things I didn't like:
1. As others have noted, the fact that she made her own lockpick and somehow practiced for hours in a variety of situations was far-fetched. Beyond the more obvious questions, where does she get access to locks? She's a peasant, right? I'm not sure locks and keys were in common posession. Maybe I'm wrong.
2. As Deaf Leper pointed out, there's a serious logistics problem with the way they're running things. If young girls are encouraged to get knocked up as young as possible, then you're going to run out of virgins sooner rather than later.
3. Why would the dragon need to wait at its cave for someone to kill it? It could just come out of its cave when the sacrifice came or circle around and block the path down to the village when the soldiers do come and they'd be forced to fight it and would quickly kill it. Or it could attack the town. And if it wanted to be killed, why did it fight the girl? The girl even asks the dragon this and didn't really get an answer--what's with that?
4. The dragon's layer of scales is described as being "like iron", but the girl cuts its toe off with a peasant's knife.
5. The priests are too aware of their own deceptions, or perhaps they are just too verbose about it. Either way, having them freely admit to the girl "Yeah we know the dragon's not really a danger, but we do it so that people will have something to dispel their fear with" is completely out of character for the priest role as described.
6. Instead of trying to make a real difference, she just sends the girls away from their parents to go live in God knows where. I find it hard to believe that none of the girls comes back, for one thing.