To help Elly get her gun from the church you first need to get into the cellar. The cheapest way is by going to the priest and letting Mira talk to him. If you don't have Mira, bribing a guard to help is possible. The bribes are cheaper with Sandra in your group. Only the guard left from the entrance and the guard looking at a flower on the right side will accept the bribe to help you.
In the cellar, you have to avoid being seen by guards. Most turn around regulary, making it possible to get through the entire map without being noticed. The chest on the bottom center can't be reached, since the guards will always see you. The room is cleared if you find Ellys gun in the box in the top left corner. If a guard catches you and you give up you'll have to pay a fine of 6000g to get Ellys gun.
Obtained from Elly at the blacksmith of Begus capital. (Map no. 31)
Retrieve Ellys gun.