WoW Upgrades - The Item Upgrader
Upgrades will give you a boost to certain stats. Each upgrade increases the level of the item by +3. Each upgrade also boosts the random substatus.
The more modernized gear generally has a higher trade value as long as it meets low requirements (like the FB sorc's shield) or very high stat variance (like the eth titan weapons). Upgrades are not as useful for the latter due to the need to roll a perfect version.
Recycle Points
The item upgrader lets players upgrade their gear by transferring the currency to an NPC. Upgrades can be applied on any kind of armor or weapons. The item used to upgrade the item will be consumed and can't be used again. Upgrades can also be used to create enchantments.
The upgrader can be found in all major cities, and can be visited at any time to upgrade your gear. It is recommended that you visit the upgrader at least once every few weeks to keep your equipment up-to-date.
The cost of upgrading will vary based on the current level of the gear being upgraded however, they will always be less expensive than purchasing new equipment from other sources. Upgrades such as upgrading a Benthic chest to ilvl385 will cost you 20 recycle points. A similar item will cost you 105.
Valorstones
Upgrades are items that can be used to upgrade weapon, armor, tool, and accessory upgrades. They can be purchased by players through NPCs who sell upgrades for items in exchange for different currencies, and can be found in random treasure lists. Once purchased, an upgrade is able to be used on any tool, weapon or armor. The button will display the preview of an item's next upgrade level, in the event that there are enough materials.
Upgrade costs vary depending on the slot for the item and the current level of the item. For example weapons cost more than bracers, or gloves. Each step costs 15 Flightstones plus a specific number of crests. Some upgrades give a discount on the Flightstones. Once upgrade item has been upgraded to a certain amount it is able to be downgraded and sold to the upgrader for a lower price.
Upgraders for items can be found in a variety of locations, including the main island and some outposts. The NPCs offer an upgrade coupon and the possibility of getting a new recipe. The upgrade discount increases when more items are upgraded. It can be increased if players finish certain achievements or quests.
Unlike Cromwell in Baldur's Gate II is no item upgrader available at the start of Icewind Dale. The NPCs who are able to facilitate upgrades are only available via a variety of ways. This is both a positive and a disadvantage.

In Season 3, several new features were added to the upgrade system. When a player has an upgrade to a specific level of an item for a specific armor slot, upgrading further items to that same item level will cost less, even in the event that they are part of another set of gear.
The discount is applicable to all accounts. In the same way, the amount of Harbinger Crests required for upgrades is also cut and is not available until players achieve certain milestones in their achievement.
Crests
Players have several options for upgrading their equipment in WoW. Flightstones are a currency that is available to all players for upgrading. Crests are more specific and are utilized during specific level upgrades for items. Crests are a crucial part of the Dragonflight Gear Progression System that was introduced in version 10.1. They come in four ranks.
First, you should know that crests are only available for gear with a certain rank. Each rank has distinct upgrade paths. The easiest and most straightforward upgrade costs 15 crests. The most complex upgrade could require as much as 20 crests, contingent on the type of gear that is being upgraded.
Players can earn crests through working through content that is of the appropriate level, whether that involves walking around and performing outdoor activities for gear of lower tiers, raids or dungeons with all difficulty for items of higher tier or Mythic+ heroic raid bosses and dungeons for gear that is used in the endgame. These crests can then be exchanged at an upgrader NPC, such as Cuzolth in Dornogal or Vaskarn in Valdrakken to obtain the appropriate upgrade routes and steps.
Using these new currencies isn't too complicated however, the system will introduce a few modifications to the upgrade process. When a piece of equipment reaches the highest level of upgrade for any rank (Explorer or Adventurer), it will no longer require Flightstones. This is to allow players to upgrade their gear up to the highest ilvl possible for all their characters rather than relying solely on seasonal loot.
Another important change is that crests have one usage and it's crucial to use them properly. For instance it's a good idea to use all of your Whelpling-rank crests on the best gear you have available, and then save Drake and Wyrm crests for the next batch of upgrades you plan on making. This is especially relevant for rings and trinkets that fill multiple slots on the character that will be able to take advantage of the account-wide discount if all slots are filled with high-quality equipment.