World of Warcraft Item Upgrades
Upgrades to an item are a way to boost the stats of an item. Based on the type of upgrade it can boost an item's Mark Level or Rarity and boost additional stats.
Each item has a track to upgrade it. Each upgrade increases the cost of the following one by a certain amount.
Item Level
The value of an item's basic stats increase when it is upgraded. This value is the total of all its upgraded benefits (attack, magic attack and defense). The cost of upgrading items can be high dependent on the upgrader and the kind of upgrade you decide to perform. This is due to the fact that many perks need to be replaced in order for the item to be upgraded.
Item level is a widely used measure of power, and can be seen on all tooltips for items. It is also used as a gating requirement when queueing for dungeons, scenarios and raids, and to limit the amount of PvP gear players can wear (since PvP is limited to a lower level). Players can see their average level of item on their character sheet.
When deciding to purchase or sell equipment players can evaluate the level of an item. It's a measure of the damage and quality. Comparing items from the inventory of a seller is possible using the item's level.
The level of the item can be checked by pressing the ALT key on PC or using the left stick (L3) on XB1 and PS4. item upgrade will be displayed with its full description, including the ilvl. You can also locate it by hovering over an item and typing in /itemlevel chat.
There are a few theories about how the calculation of an item's level is carried out. One theory suggests that the level of an item is calculated using formulas that determine the worth of an item's stats really are. It is based on the fact that different benefits are valued differently and that gems in the sockets boost the value of the item. This could result in an item's ilvl which is calculated and is typically very close to Blizzards actual item level.
However, this isn't the only factor which can affect an item's ilvl as the level of the region the item was dropped in could change the value of its stats, such as by adding an amount to its haste or crit rating. Items that drop in higher-level situations will have a higher ilvl.
Item Stats
The stats of an item are a major part of what determines the value of an item for players. The game uses them in many ways to encourage players not to limit themselves to one weapon and to encourage players to explore other weapons. The stat modifications of a weapon boost the base stats. These stat mods are then increased by a player's skill.

The upgrades to an item can boost its stats. The rarity of an item determines the cost of upgrading. For instance, a grey or white item will only be upgraded once, whereas an item with the rare tiers will be upgraded several times with higher prices.
Affixes can also be used to change an item's stats. They are stat boosts which can be added by the player to an item. Affixes can provide the item extra damage, or add a unique capability to the item (such as reviving the dead or decreasing the cooldowns), or make the item unique by putting an exclusive name to the item.
At present, all affixes can be changed by selecting them from the upgrade window and pressing the green button using circles arrows. This procedure will cost the player a certain amount of gold and items, which can be added to the upgrade gauge in the same way as other options for rerolling.
Players can choose to upgrade an item with a specific stat, or reroll affixes. The possible ranges of stats for an item are determined by the item level, but every item is guaranteed to have at minimum one stat within that range, unless it's a unique item or the result of a God roll from a raid boss.
Another thing that could be changed is the option to upgrade equipment without having to roll the attaches, or select which stats to enhance. However, as with the base equipment, this would need to be done on a per-item level, and the interface for item comparison will not show all the stats that could be that were gained or lost at the same time.
Item Luck
The Luck stat of a player increases the likelihood of locating items and the properties that are created by loot and the intensity of these properties. However, it does not directly affect damage or the ability to upgrade items. It gives players the chance to upgrade their gear earlier in the game. This is especially useful in the early game, because players tend to put defenses and weapon scaling over raw damage gains.
Luck can also increase the chances of upgrading items at the Blacksmith. This is not to be confused with the Blacksmith's overall chance of upgrading that increases with each level of the item and can be further enhanced by using an anti-material, such as a Scroll of Strength or a Jewel of Blessing.
Armor, shields and weapons have a default Luck value of 40. These items can then be enhanced by golden ingots, spined leather, or oak boards (depending on the material of the item) to grant an additional +40 Luck, or to increase the existing Luck of an item up to 140.
Moreover there are certain items, like the Hollow weapon, which is infused with Hollow can be used to increase the damage of any damage-dealing skill by 5%. These items can be purchased at the store or made using the correct ingredients.
Item Failure
Upgrades to items can be a costly process and not every upgrade will be successful. Cash shop items can be used to increase the chance of success of an upgrade or to stop players from losing their item in the event that it fails.
item upgrades of an upgrade is shown in the Honing UI. The percentage is the probability of successfully upgrading the item. This can be increased by using Additional Materials or Special materials. The percentage of success can only be increased as high, and the probability that an upgrade will fail can't exceed 100%.
The Luck of an item may influence the success of an upgrade. Each item has a base success rate of 25%, and every item with Luck increases the chance of success by 5percent.
Note that upgrades to items are rendered above the inventory items which means that enchantment glints and other effects may be masked by them. If you wish to disable the upgrade overlays, the config option decoration.renderUpgradeOverlays can be set to False in the Item Upgrader CORE client config.