So you're probably thinking right now, "Girlinhat's probably broken the game" and you'd be right. Because that's what I do. There's a set of game mechanics in place, and I game them until it bends to my will. For today's breaking? Weapon upgrades!
There are 5 types of ways to upgrade your weapons.
1: Grind - Spend Grinders and raise a normal weapon to +1, then +2, etc, all the way to +10. Each grind adds
about 5% to attack values, capping at a clean 150% power at +10. This mean your weapon that does 100 damage will end up doing 150 after grinding.
2: Attributes - A weapon can have one attribute, an element. This shows as an elemental icon, with a number, alongside the normal damage listing. It adds (element_power/100)*weapon_power attack value as an extra elemental damage. This means that your 100 damage weapon with 50 Ice would deal 100 physical damage and 50 ice damage - when you make an attack, it will simply pop up as "150" floating number. This also means that your 100 damage weapon grinded to +10 would deal 150 physical damage and 75 ice damage.
You can raise the elemental damage of a weapon by sacrificing other weapons. The sacrificial weapon must be the same rarity - it works better if the weapon has the exact same name, and EVEN BETTER if the weapon has the same name and elemental damage. The maximum is 50.
3: Extension - You can spend rare materials to craft your weapon higher, using the 'crafting' system. It's best to get started on this as soon as you start playing, because you have freely available 'daily crafts' that consume no resources, but reward you with resources, crafting skill experience, and other rare items related to crafting. You WILL need this later. What extending does, is it raises essentially any weapon towards the natural damage ceiling. At maximum extension and +10 grind, all weapons of the same type will have the same damage value. A 7star Red Processor and a 1Star Rod, both maxed out, will have the same base stats. Lower rarity items take more extensions, while higher rarity items take fewer extensions to reach the same point. It will also raise the stat requirement to wield the weapon, so be sure you have enough stat to wield the post-extension weapon!
NOTE: Extending an item will remove any hidden or class quirks. 7star+ weapons have an unlisted damage variance of 90%-100% while 6Star- weapons have 55%-100% variance, and your Dex stat helps bring that closer to 100%-100%. Grinding a 7star will revert that 90%-100% to a 55%-100% so your damage rate may drop, initially. High-level players of any class except Braver (who sometimes lacks dex) don't have to worry about this. Young characters using hard-won rare items can suffer, temporarily. Similarly, if the weapon has any multi-class abilities that are unusual for that weapon (a rod that a hunter can wield) then that will be lost. HOWEVER an extension also has the ability to add multi-class options to a weapon!
Potential - When you grind a weapon to +10 you can unlock its potential, which will cost photon spheres (so it's costly) and reset its grind to 0, but give it a unique ability, like +10% damage to forest creatures, or +10% fire damage. There's a list of potential abilities, some are better than others. You can unlock potential 3 times, to a total of level 3, which will require 30 grinds up and a cluster of photon spheres.
List of potentials:
http://pso2.cirnopedia.info/potential.phpAbilities - The real issue here. While other weapon upgrades are fairly straightforward, like throwing grinders or elemental weapons at an item, Abilities are more quirky and costly. They can be valuable, such as adding straight T-ATK or straight T-DEF, or perhaps most importantly, adding +PP. The problem is the existential grind of collecting these items. You see, to raise an ability, you need more items with that ability. Luckily, any weapon can upgrade any weapon, you don't need them to match at all, but armor cannot upgrade a weapon.
There's two types of ways to upgrade abilities, by depth and by width. That is, you can make one ability better, or you can add more abilities, or both. Preferably both.
First the depth, to make one ability better. You have to either find an existing high-value ability, or combine low-value abilities. Technique I gives +10 T-ATK, while Technique II gives +20 T-ATK. To upgrade from I to II, you need to combine 2x or 3x of I's. Combining 2xI will give you a 60% chance of upgrading to a II. Combining 3xI will give you 80% chance of upgrading to a II. This means you'd need 3 separate items, each with Technique I, select one as the target of upgrade, and sacrifice the other two items. Going from II to III (which has +30 T-ATK) would give you a 30% or 50% success rate, if you're combining 2 or 3 items with II. This means, ideally, you'd be burning 2 items into 1 each step.
To hit Technique II, you'd need 3 Technique I's. (80%)
To hit Technique III, you'd need 9 Technique I's. (50%)
To hit Technique IV, you'd need 27 Technique I's. (40%)
To hit Technique V, you'd need 81 Technique I's. (30%)
These abilities can be transferred, painfully. Moving a I to an empty weapon has 100% success. Moving a II to an empty weapon has 60%, and it gets worse from there, with moving a V value ability to a weapon, intact, has a 10% success rate. You can improve this by sacrificing multiple of the same ability. If you (somehow) have 3 items with Technique V, and want to change one ability on one of them, you can combine all three items, giving you a 50% chance for your Technique V to remain intact. This failure chance ALWAYS occurs any time that weapon is used in an ability transfer. If you've got a weapon that already has Technique V, and you want to add a different ability to it, then keeping the Technique V would only have a 10% chance. This makes your existing high-level ability weapons rather important and difficult to add new abilities to them.
That's for ONE ability. For TWO abilities (the width), such as Technique for +T-ATK and Spirita for +PP, you'd need to expand a 1-slot weapon to 2-slot. Expanding slots has a failure chance, which raises as the number of slots raises. To raise slots, you'd combine a 1-slot and a 1-slot weapon into a 2-slot - such as you have one weapon that has Technique I, and another that has Spirita I, you may want to combine those to get Technique and Spirita on the same item. These I's normally have a 100% success rate, but because you're trying to add a slot to an item, you take a penalty, in this case 90%. If you've got one item with Technique II (60% transfer rate) and a second with Spirita I (100% rate) and try to combine them into one item with both abilities, then you'd have (.60*.90) = 54% rate to add Technique II and (1.0*.90) = 90% rate to add Spirita I.
But wait, there's ways to raise the transfer rate! Two ways, in specific. The first are consumable items. The best booster is +30% flat success rate, and comes at the cost of 20 excubes. When your character hits level 70, every time they'd normally gain a new level, they instead gain 2x excubes. This makes those 30% booster items quite valuable, as you have to gain 10 levels over cap, and means experience is always valuable.
The other method is boss souls, items gained from the big red crystals that bosses drop when they die. If any weapon involved in an ability transfer has a boss soul on it, that soul will be burned and a boost will be given to the transfer rate. MOST weapons with boss souls are only 1 or 2 slot items, but if you have 3 weapons, one is blank, the second has a boss soul, and the third has the same boss soul, you can expend those to put the boss soul on the first weapon - unlike normal abilities that transfer normally, a boss soul can ONLY be transferred if you have 2 or more of that soul in the mix.
So, you may be asking, that's all well and good Miss Hat, but what's the practical breakdown? Well here it is... it's a lot of planning.
Step 1: Decide what abilities you want to have at the end.
http://pso2.cirnopedia.info/abilities.php I suggest +ATK +PP and one boss soul. Due to limitations, you CANNOT get 2 boss souls on the same weapon - you'd need to combine 4 different weapons to accomplish this, which isn't possible. The fewer abilities you choose, the easier this will be.
Step 2: Get 81 weapons that each have that ability at level I, including your target weapon. If you want a boss soul (and you do) then make sure each weapon has the same soul, so prepare to grind one particular boss a lot.
Step 3: Start fusing those weapons, combining I's into II's and II's into III's until all 81 have been forced down into one weapon that has all of them at V's.
Why is this so?
You could technically work with only 54 of the boss souls, but what they give importantly is a boost to transfer rate, which is important.
Combining abilities has a higher success rate than moving an ability. So you do NOT want a weapon with Technique V and a weapon with Spirita V and toss both of those onto the same weapon. If you're combining those onto a 1-slot weapon, you'd only have a 9% success to raise the slot number and add those abilities. If you were adding those two from separate weapons onto a weapon with 2 slots already, it's still only 10% success. However, if you have IV and IV and IV and combine them onto the final weapon, that's a 30% success rate. Start adding in boss soul burns and those excube 30% boosters, and things start to look a lot better.
The good news?
ANY weapon works. If you want 3 final abilities, then ANYWHERE you find those abilities, on any weapon, can go into the mix. You simply need to start pairing up weapons to combine slot values and end up with 3-slot weapons that have the abilities you want, which has a decent success rate when you're only dealing with I's and low slot numbers.