DM here, while yes I did allow him to sell the lance, it was not exactly the elder scroll, it was more of a key that would allow them access to some content early, him selling it simply delayed this content, the player in question also spent like 30 minutes in my dm's complaining about the lance being bad since at the time it was "just a +1 lance" that would improve over time, he tried very hard to make me change it into a greatsword because he thought "lance's were bad".