Instructions
Purchase an "Empty Bottle" or find one by killing monsters.
Find a water source in-game. There are multiple ponds on the map, including one west of the city of Prontera, one in Comodo and another west of Geffen near the town's bridge.
Select the "Empty Bottle" from your item inventory and use it while standing in the pond. This will fill up the bottle with water and return it to your inventory.
Cast the "Aqua Benedicta" spell using your Acolyte or Priest character to create "Holy Water" from the full bottles. If you do not have an Acolyte or Priest character, connect wirelessly with one of your peers who do.