WoW Upgrades - The Item Upgrader
Upgrades provide a guaranteed boost to specific stats. Each upgrade increases the item level by +3. Each upgrade also boosts an unspecified substat.
The upgraded gear is usually more valuable, unless it is not required by nature (like FB sorc shields) or has a large variance in stats (like eth Titan weapons). The latter see less value from upgrading due to the need to roll to get 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 be used to create the enchantments.
The upgrader is located in all major cities and can be accessed anytime to upgrade your gear. It is recommended to visit the upgrader every few weeks, to keep your equipment up to date.
The cost of upgrading will vary based on the current item level of the gear being upgraded, but will always be cheaper than purchasing new gear from other sources. Upgrades like upgrading a Benthic chest to 385 ilvl will cost you 20 recycle points. If you purchase a similar item, it will cost you 105.
Valorstones
Upgrades are items that can be used to purchase weapons, armor, tools, and accessory upgrades. They can be purchased by players from NPCs that sell upgrades to items in exchange for different currencies, and can also be found in random treasure lists. Once an upgrade has been purchased, it can be used on any weapon, tool, or armor using a button, which will show an item's preview at its next upgrade level if the player has sufficient materials.
Upgrade costs vary depending on the slot for the item and the current level of the item. For example weapons are more expensive than gloves, bracers, or bracers. Each upgrade costs 15 Flightstones plus a certain number of crests. Certain upgrades provide a discount on the Flightstones. Once an item is upgraded to a certain amount it can be re-downgraded and sold to the upgrader at a lower price.

Many locations offer item upgraders in addition to the main island and some outposts. The NPCs provide both an upgrade discount and a chance to get a brand new upgrade recipe. The upgrade discount increases as more items are upgraded. It can be increased if players finish certain achievements or quests.
Unlike Cromwell in Baldur's Gate II there is no upgrader for items available in the beginning of Icewind Dale. Instead, the NPCs that can be used to upgrade require several methods, which is both an improvement but also a drawback.
In Season 3, a number of new features have been added to the upgrade system. After a player has earned an upgrade to a particular level of an item for a specific armor slot, upgrading other items to that same item level will cost less, even if they are part of another set of gear.
The discount is applicable to all accounts. The amount of Harbinger Crests required to upgrade is cut too, but it is only available once certain milestones are reached.
Crests
When upgrading gear in WoW players have a couple of options. They can make use of Flightstones which are a general upgrade currency that is available to all players, or crests, which are more specialized and consumed during upgrades at specific levels of the item. Crests are an integral element of the Dragonflight Gear Progression System, which was introduced in version 10.1. They come in four ranks.
The first thing to remember is that the crests can only be purchased for equipment of a certain rank. Each rank has a different upgrade path. The simplest and easiest upgrade is 15 crests. upgrade item complicated upgrade requires up to 20 crests, contingent on the type or equipment being upgraded.
Players can earn crests by completing tasks at the appropriate level. This could be done by doing outdoor activities, or by completing dungeons and raids in all difficulties to get equipment of lower tier or Mythic+ raid bosses or dungeons that have a high difficulty for endgame gear. The crests can later be exchanged at an item upgrade r NPC, such as Cuzolth in Dornogal, or Vaskarn in Valdrakken to get the appropriate upgrade routes and steps.
Utilizing these new currencies isn't too difficult however, the system introduces some modifications to the upgrade process. When a piece of equipment attains the highest level of upgrade for any rank (Explorer or Adventurer) it is no longer required to purchase Flightstones. This change allows players to upgrade their gear to the highest possible level on all of their characters rather than relying on seasonal loot.
Another notable change is that crests only have one usage, so it's important to make use of them in a responsible manner. For instance, it's best to make use of all your Whelpling-rank crests on the top equipment you have and then save Drake and Wyrm crests to use for the next set of upgrades you plan to make. This is especially applicable to rings and trinkets that fill multiple slots on the character, which will only be able to take advantage of the account-wide discount when all slots are filled with high-quality gear.