Wanted to know how this "stone" thing work (waterstone, etc )
Some say it gives atk some say it gives def?
Can someone tell me what they know about it?

blessing stone is for evolving summons/pets.
u need 10 blessing stones per stage of evolution.

well can you tell me what the different elements do when you mix weapons? ( wind fire water and earth)

well actually blessing stones can be used for summons but also for enchanting weapons or as u call it 'adding elements to ur weapons'. when u enchant a weapon there are specific steps you must follow to do this. here are the steps:

1. Get 2 of the same weapon, preferably one weapon being stronger than the other.
2. Open up the inventory window and select manufacturing at the bottom.
3. You'll see a window pop up. At the top of the window, click on mix.
4. Place the weapon you want to have enchanted in the 'Power-Up' box. Place the other weapon in the 'Normal' box.
5. At the bottom, you'll see 4 types of elements. Fire, Wind, Water, and Earth. Select the element you want to add to your preferred weapon.
6. At the very bottom, click enchant and watch the magic.

This is basically what you do. If you notice when you enchant a weapon, it will have the attribute rank on it. The number is it's level. You can increase it's level by getting the same weapon again plus a number of stones. However, as you try to increase the attribute rank/level of the weapon, the success rate will drop. This is where blessing stones come in. They gurantee the process of enchanting with 100% success. Depending on what level you are enchanting to, the number of stones will be needed as follows:

From Level 1 to Level 2 - Two of the same weapon with one weapon at attribute rank 1. Requires 5 stones that must be the same element as the weapon you want to enchant. One blessing stone can be used if you want 100% success on the enchanting process.
From Level 2 to Level 3 - Same requirements however you need 10 stones and 2 blessing stones if you want 100% success.
From Level 3 to Level 4 - Same requirements however you need 15 stones and 3 blessing stones if you want 100%. (I am not sure of this i'll try to confirm it.)

This is all there is to it. It'll cost a lot of money but it may be worthwhile in the end. If you have any other questions, ask away ^^