Written by MSG Commander
There are two basic parameters for weapons: ATK, and Added Effects.
Determines how much damage your weapon does. ATK also plays a role in how much damage you do when using physical break skills and unisons.
You can raise your weapon's ATK by choosing Upgrade, and adding multiple weapons to your base weapon. Each weapon you add raises the base weapon's EXP, and when the EXP gets high enough, the ATK levels up.
Each weapon can have up to four added effects. When you Upgrade a weapon, if your base weapon and the weapon you're adding both have the same effect, you can raise the % value of that effect.
In order to raise the value, the weapon you're adding must have a value of 10 or higher. (Every 10 points on the weapon you're adding translates into 1 point added to your base weapon.)
For example, if your base weapon has STR 15, and the weapon you add has STR 42, 42/10 = 4 (with a bit leftover), so the weapon you're adding will raise the STR effect by 4 points, for a new total of 19.
(In a case like this, however, it would be much wiser to use the weapon with STR 42 as your base weapon, and add the STR 15, for 1 point, so that your new STR rating would be 43. Then of course, if you find enough weapons to get that STR to 50 or higher, then you can transfer it to any weapon of your choosing.)
Along with upgrading an effect, you can also transfer effects to your base weapon as long as the effect you're transferring is at least 50%.
In order to transfer an effect from a new weapon onto your base weapon, these two things have to happen:
1. The effect you're transferring must be 50% or higher.
2. You must have an empty slot on your base weapon, for the effect to transfer to.
The game will automatically choose the effects that are high enough to transfer, and it will transfer those effects in order from left to right.
(So if you have a base weapon with four empty slots, and you're transferring two effects, they'll be placed in slots one and two. However, if you only have one empty slot, you'll only be able to transfer the first effect, so in a case like this you'll want to choose carefully.)
Effects that are 50% or higher can be transferred repeatedly, from one weapon to another. (So every time you find a new weapon with a higher ATK, you can move your 50% effects onto that weapon. The only effect that does not transfer is Swoon, so if you really want that effect, you're stuck with whatever weapon it's attached to.)
You can also remove an effect from any weapon by using a Deletion Fossil - however, these are hard to come by so you'll have to decide which effects are worth removing.
Also, even though effects are added from left to right, they can only be removed from right to left (meaning if you have three effects, the Deletion Fossil will let you remove the third effect only, not effect one or two.)
So, you'll have to choose which effects are most important to you, and either look for weapons that have that effect (with a high rating), or look for empty weapons that you can transfer the effect onto.
The most popular effect by far is Critical, which is essential for defeating metal monsters. (You can also use the Metal Arkstone and 30 Arkstone to defeat most metal monsters, but as far as effects are concerend, Critical is the only one that will damage them at all.)
Some other popular choices are HP Recovery, HP, STR, SPD, and VIT. (Another good choice is Steal - especially if you want to farm weapons or items from high level monsters.)
Swoon can also be fun to play with - but Swoon is not transferrable, so if you want this effect, you have to find a weapon that has it, and then keep that weapon until another weapon with Swoon also comes along, which can be a pain, but if you like using Swoon, I guess it's worth it.
Raising an Effect to 50
It can take a bit of time and effort to raise an effect to 50, but for the right effects, the effort will pay off.
What you want to do is first identify the effects that you want. (I use Critical and Steal, and then some variation of STR, INT, VIT and SPD, depending on the character and on whichever of those effects I happen to obtain first.)
Start collecting weapons that have the effect you want (with a rating of at least 10!) When you get one that's in the 30's, go ahead and use that as your base weapon for raising that particular effect, and add as many weapons as it takes to get the rating to 50.
(For example, say you find a weapon with Critical 32. Take all your other weapons that have Critical of 10 or higher, and start adding them onto that weapon until the rating is 50. Now, you can transfer that Critical to any weapon you want!)
Note: If you're a casual player, then customizing your weapon's effects isn't really that important. It is advisable to use weapons that have a high Critical effect, because that's one of the easiest ways to kill metal monsters, but otherwise it really doesn't matter what effects you have.