World of Warcraft - Item Upgrading
The item upgrade allows players to boost the gear rating of an item by up to 700 points and give it a bonus. Items can be upgraded if they are in your inventory and you decide to take them to the Kiln.
Certain items can be upgraded to increase their stats (like a perfectly broken point armour that is rolled for melee PvP) while others like weapons do not change significantly after an upgrade and thus aren't worth upgrading.
Weapons
Upgrades to weapons can improve their numerical stats, such as attack damage, crit chance and PvE/PvP damage. Weapons also have an unchanging bonus that increases the damage they deal per second. Some weapons also have an unaffected bonus that is activated when three or more identical weapons are equipped in a unit. In some cases this bonus could amount to more than the amount of damage a weapon can sustain on its own.
The cost of upgrading a weapon's capabilities is contingent on the rarity of the weapon and its current level. For instance, a +2 weapon will require two standard Smithing Stones while a+3 requires four. The number of stones required to upgrade a gun will increase until it requires more Smithing Stones. At that point, it will reset back to one.
Upgrading weapons will also reroll their base stats. While this is usually beneficial, it can have some negative consequences too. For items that are only used in a specific build (Whistant's shield for FB sorcs for instance) upgrading them can render them unusable unless you get a lucky roll.

It is possible to upgrade armor items to improve their effectiveness. In the case of a helm or chest, it will boost the defense of its base, while a belt and gloves will improve their required strength and dexterity. Armor also has a reroll option for its Enhanced Defense percentage, which means that it can sometimes change its roll to a lower value.
The upgrade template of a weapon will show the new stats that it will gain after upgrading along with the relative value of those stats. This means that an upgrade from a sword that has 8 damage to an 11-attack-damage sword would result in the weapon gaining an attack damage of 3. The 3% does not mean that the weapon will strike 3 times less, as it is an absolute number.
A weapon can be rerolled by pressing the green button, which is accompanied by arrows that circle in the menu for items. This will roll an item and alter its stats, but it will not reset the weapon's levels, or tie it to the account status.
Armor
A few armor upgrades can make a huge difference to your survival. Certain sets can offer massive increases in resistance to poison, curses and fire as well as magic. This makes it easier to traverse difficult areas. In general, the more defense you can offer your character, the greater health you can get from each point. So, it's best to upgrade your armor.
To improve your armor, head to any of the Great Fairy Fountains in the game. There are four in total and each one requires you to complete a unique side-quest involving the Stable Trotters musical troupe. Once you've completed the primary side quest and completed the fountain that corresponds and then you can talk to any Great Fairy to open up the armor upgrade menu.
The amount of materials required to upgrade each piece of armor will differ. You'll require anything between three Red Chuchu jelly and 10 Rupees to upgrade the initial armor piece, and between five Rubies or 10 Fire-Breath Horns to upgrade the next one. For example, the Champion Leathers can be upgraded to +5 defense, which allows you to keep up with a decent-sized group of enemies in most cold climates and the Snowquill Headdress can be upgraded to +20 defense, giving the protection needed to survive a full on raid with a handful of friends.
Note that armor can't be upgraded in the same manner as weapons, so you'll have to work on upgrading it for physical power if you're Warrior or Spell Power when you're Mage. It's also worth saving your armor upgrades for armor you'll still be wearing at the end of the game, such as the Ring of Lightning and Spectral Shield or the helmet you use to fight the final boss, the Monter Parts Merchant's mask.
By giving the jeweler 10 Twinkling Titanite in Gerudo Town and you will be able to gain some benefits to your armor. It is generally recommended to save these upgrades to the weapon that you'll use to beat the game. For example the Longsword or Battleaxe. But it's useful to have some upgrades for the helmets and chest armor to let you get around a few monsters.
Potions
Potions are liquid substances that, if consumed, give the user a temporary status effect. There are item upgrading of potions, each with particular effects and durations. Certain potions can be upgraded to enhance their level of effectiveness. In addition, the effects of some potions can be enhanced by adding redstone or glowstone dust to the potions.
Potion upgrades require a certain amount of XP. This can be obtained by making them on a table, or by storing them in the Alchemist chest. The upgrade price varies depending on the type of potion as well as the item's rarity as well as Mark Level.
To upgrade a potion you need to right-click it in your inventory. Select "Upgrade" from the menu. This will open a GUI which allows you to select the potion you would like to upgrade and the amount of experience they will give you when upgraded. You can upgrade potions in batches up to five at once, and their XP will be added to the total XP you have.
Once a potion is upgraded in quality, it will not deteriorate in the event that you use it again or break the bottle within the container it is kept. Clicking on the potion in your inventory will allow you to change its name.
There were a few updates to the mechanics of potions in version 1.7.2. For instance splash potions now have a duration of 0:08 (this is not the same as the 22.5 seconds shown on the hover display for the item). The table of potion can now be constructed using four Wood Planks and two Glass. This allows it to be used by players in Survival and Bedrock. In contrast to the Java Edition, Bedrock edition potions cannot be mixed in cauldrons. Similarly, using a potion in a cauldron that is full drains the liquid and refills the bottle.
Finally, there are simmering potions made with dragon breath and splash potions. Redstone is also added to lingering potions to extend their effect. The table of potion ingredients is now laid out more in line with the Java Edition, and new potions were added, such as potion of leaping, decomposition potion, and turtle master potions.
Trinkets
A trinket is a small, inexpensive ornament or piece jewelry. It can also refer to a small ornament or object that serves a function but isn't important as a trinket. In some cultures a trinket is used to show affection or friendship between family members.
In addition to weapons, armor and potions, players are able to upgrade their trinkets. Upgrades can be made by paying the appropriate currency to an upgrade vendor. Trinkets unlike other items that can be upgraded, can be exchanged at any time without losing statistics.
Upgrade vendors are located at the capitals of every zone, and in some instances in dungeons. Upgrades for trinkets are offered using tokens, gold or fragments of trinkets that are rare.
Upgrades are a less expensive alternative to buying a brand new trinket. One can upgrade their trinket for just 12 tokens. The new trinket will have the same base ilvl of the older one, and have an additional upgrade bonus of 1.
When the old Trinkets are no longer usable, they can be upgraded. This allows a player to increase both their power and value with time. They can also be traded between players, making them an attractive alternative to gold.
In general, players should upgrade their most important items first. This means that the top-in slot items for each class are upgraded first then their secondary gear and finally other pieces of equipment they won't be replacing in the near future (such as a ring or an cloak). It is also important to consider your class's preferred stats when selecting the items to upgrade. If Haste and Crit are two of the most important stats for a tank player then they should consider upgrading their chest, helm, and shoulders.
Trinkets are able to be upgraded to a higher ilvl once they are no longer useful, and the new trinket will have an additional bonus of 1% for upgrading. However, a re-upgrade will ruin the previous trinket, unless it is salvaged with a Black Lion Salvage Kit or a higher-tier salvage tool. This makes upgrading trinkets more expensive than other upgrades, however it is still cheaper than buying the new one.