Quite a little bit of work there, but I'll tell you what you need to do.
This is assuming you're using PI.
First, you need to go to Actionhandler and send the options of each weapon. This can easily be copied with any teleporting method.
You must then make the buttons work by going to ClickingButtons. You must have it check if they have the required amount of holy waters to purchase an item.
Here's random samples.
Code:
case OBJECT_ID:
sendOption("Anger Mace", etc. etc. etc. etc.);
dialogueAction = ID;
break;
Code:
if (c.getItems().playerHasItem(HOLY_WATER_ID, AMOUNT)) {
c.getItems().deleteItem(HOLY_WATER_ID, AMOUNT);
c.getItems().addItem(ANGER_WEAPON_ID, AMOUNT);
c.sendMessage("You've purchased an anger weapon.");
}
I would help via more specifics but I don't have my base codes with me, sorry.
EDIT: Also apologies for no conventions. Just typed this up right now.