As some of you may have already noticed, there exists a kind of item that is dubbed a Soul Gem, currently for sale in the shops in Erisia. Those who noticed that may have also noticed that, directly above the Soul Gems, there is an equip item that, at the end, dubs itself to have 1 Slot. This is no coincidence, as these Soul Gems serve to be put into equip items and yes, even Soulbound Weapons. So let's start with the guide, shall we?
-What is a Soul Gem?
In the lore, a Soul Gem is a crystallized mass of magic made to amplify someone's powers when slotted into a weapon or armor piece. All bought pieces of gear tend to be compatible with these Soul Gems unless they are stated to have 0 slots, in which case, they cannot be input into them. The Soul Gems can boost many a thing, and the higher their Tier, the stronger the boost they will give. Example:
Agility Gem I: Soul Gem that increases Luck by 5 points.
Notice the I in the name? That's the Tier. Soul Gems can have up to five Tiers, just like skills, and each Tier can be input into any equip item as long as the Soul Gem is gotten. For example, a Tier II item will naturally be better to input into an equipment with one slot rather than its Tier I counterpart. In your compendium, you should list the Soul Gems you currently have equipped, but to make it simpler, just add all your available slots together and work off that, it doesn't matter where the Soul Gem is, it'll always give you the same boost, so just count them as a different equipment slot. The number of slots you have for these Gems is obviously dictated by what you have equipped. Not to mention, Soulbound Weapons, which can't be unequipped, automatically start with 1 slot, so you will always have at least one Soul Gem slot available to fill in.
-How do you get Soul Gems?
Aside from the obvious buying them from stores deal, some enemies will also drop Soul Shards, which can be combined to make Soul Gems using a Soul Furnace, which can be found in any city. These Shards will display the amount of whatever element they add to a Gem, and once that element reaches 100%, you can make a gem of the Tier the Shard has. Reach 200% and you can make a Gem a Tier above what the Shard has; useful! Some Shards, though, will give more than one element on many occasions. When such happens and you have a sufficient amount of one element to make a gem, you can store the remaining amount of the other into a Soul Cylinder for free, which you can then combine afterwards with more Shards to create more Soul Gems. Making the Gems costs a small fee, depending on the Tier of the Gem you're crafting. These prices will be listed at the shop.
-You spoke about Upgrades before, what are these?
Upgrades, simply, are ways to boost your equipment higher than it normally would go, up to a certain point. Regular store-bought equipment always has 3 upgrades available to it, while a Soulbound Weapon has a total of 7. Upgrading can be used to raise an equipment item's stat increase, give it more slots and even change its appearance while you're at it. For Soulbound Weapons, it can raise its Tier by 1 (for a very large fee), add another element to it (only once), or give it an extra Soul Gem slot (up to a maximum of four extra, for a total of five). It is up to you how you want to upgrade your equipment, but some combinations can get very powerful in the long run. Prices for all upgrades will be listed at the Upgrades shop when it goes up; these will vary with the item Tier, its current slots and increase.