World of Warcraft Item Upgrades
Upgrades to items can be used to boost the stats of a particular item. Based on the type of upgrade, it may raise an item's Mark level or Rarity, as well as boost other stats.
Each item comes with a track for upgrading it. Each upgrade increases the cost of the next one by a specific amount.
Item Level
When an item is upgraded, its base stats increase in value. This value is the sum of an item's upgraded perks (attack magic attack and defense). Upgrades to items can be costly, depending on the upgrader and the type of upgrade you choose to perform. This is due to the number of perks that need to be modified to upgrade an item.
It is also used as a gating requirement while waiting for dungeons, raids and scenarios. It also serves to determine a gating condition when waiting for dungeons, scenarios and raids, and to limit the amount of PvP gear that a player can wear (since PvP is restricted to the lower levels). The average level of the item can be found on the character sheet.
Utilizing the level of an item can help players evaluate the strength of equipment when choosing to buy or sell. It's a useful gauge of an item's worth and how much damage it's capable of causing. Comparing items in the inventory of a seller can be done using the level of the item.
On PC, you can view the item level using ALT, or by using the left stick on XB1 or PS4. This will show the item's full description, including ilvl. You can also locate it by hovering over an item and typing /itemlevel in chat.
There are various theories about how the item level calculation is done. One theory is that the item level is a number that comes from a formula which calculates the amount an item's stats are worth. It takes into consideration the fact that different perks have different values and that gems in sockets add to the value of the item overall. This can lead to an item's ilvl calculated, which is usually very close to Blizzard's real item level.
This is not the only factor that influences the level of an item. The level of the area where the item dropped can also alter its stats. For example, it could add a level to the item's haste, or crit rating. This means that items dropped at higher levels will have higher the ilvl than items from lower level instances.
Item Stats
Item stats are a big component of what determines the value of an item for players. The game utilizes them in various ways to encourage players to not limit themselves to a single weapon and to encourage them to try out other weapons. The base stats on a weapon are increased by the weapon's stat modification which are then increased by the player's skill.

Upgrades to an item can increase the stats of an item. The rarity of an item determines the upgrade cost. An item that is white or grey for instance, can only be upgraded once however, items that has rare tiers can be upgraded multiple times with higher prices.
Another method to alter the stats of an item is through affixes. These are special stat boosts that can be added to an item by the player and are available in all sizes and shapes. The affixes are used to give items extra damage or other special abilities (such as revitalizing dead or reducing cooling downs), or to distinguish them by adding a name.
All affixes can be currently re-rolled by selecting them in the upgrade menu and pressing the green button. It will cost a set amount in gold and items. They can also be used as upgrade gauges, as with other methods of rerolling.
In addition to rerolling affixes, players can select which stats to keep on an item after it is upgraded. The possible stat ranges of an item are determined by the level of the item, but all items are guaranteed to have at minimum one stat within the range, unless it is an exclusive item or a God roll from a raid boss.
Another thing that could be changed is the possibility of upgrading equipment without having to reroll attaches, or select which stats to increase. But, like base equipment, this would have to be performed on a per-item basis and the item compare interface wouldn't show all possible stats that were gained or lost at the same time.
Item Luck
The Luck stat for a player adds up to increase the likelihood of item discoveries as well as the properties that appear on loot drops and the intensity of the properties. However, it doesn't directly affect damage or the ability to upgrade items. It simply gives the player a chance to upgrade their gear in earlier waves, and is therefore more useful in early game runs as opposed to later ones, because most players value more powerful weapon scaling and defenses over damage gains.
In item upgrader to influencing item discovery, Luck also increases the chances of success when upgrading items with the Blacksmith. This should not be confused with the Blacksmith's overall chance of upgrading, which 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.
The shields, armor and weapons come with an initial Luck value of 40. These items can then be upgraded with golden ingots, spined leather, or oak boards (depending on the item's material type) to grant an additional +40 Luck or to boost the luck of an item, up to 140.
Certain items, like the weapon that is infused with hollow, can also be equipped to increase the damage dealt by any ability that is able to deal damage by 5%. These items are available in the shop or created using the right ingredients.
Item Failure
Upgrades to items are costly and not all upgrades will succeed. However, there are some cash shop items that allow players to increase their chance of success or stop themselves from losing an item in the event that the upgrade is unsuccessful.
When you upgrade an item, the rate of success is displayed in the Honing UI. The percentage is the probability of successfully upgrading an item. This can be increased by using Additional Materials or Special Materials. There are limitations on the extent to which the success rates can be improved and the chance of an upgrade failing can't exceed 100%.
The performance of an can be affected by the luck of that item. Each item has an overall success rate of 25 percent, and each item that has Luck increases the chance of success by 5percent.
Note that upgrades to items are rendered above the inventory items therefore enchantment glints and other effects can be obstructed by the overlays. 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.