Why We Do We Love Item Upgrade (And You Should Too!)
WoW Upgrades - The Item Upgrader
Upgrades will give you a an increase in certain stats. Each upgrade increases the level of an item by 3. Each upgrade also boosts a random substat.
upgrade item upgraded gear typically has a more value in trade as long as it meets low requirements (like the FB sorc's shield) or a very high stat variance (like eth titan weapons). These types of gear get less value from upgrading due to the necessity to roll for a perfect model.
Recycle Points
The item upgrader allows players to upgrade their gear by transferring the currency to an NPC. item upgrades can be made 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 the enchantments.
The upgrader can be found in all major cities and can be visited anytime to upgrade your equipment. To keep your gear current it is recommended you visit the upgrader each several weeks.

Upgrades can cost more based on the item level, however they'll always be less expensive than purchasing new gear. Upgrades such as upgrading a Benthic chest up to ilvl385 will cost you 20 recycle points. A similar item will cost you 105.
Valorstones
Upgrades are items that can be used to purchase weapon, armor, tool and accessory upgrades. They are purchased by players from NPCs that sell upgrades to items in exchange for a variety of currencies, and can be found in random treasure lists. Once purchased, an upgrade can be used on any weapon, tool or armor. The button will show the preview of an item's next upgrade level, if there are enough materials.
The cost of upgrading is based on the slot of the item and the current item level and the weapon's price is higher than bracers or gloves, for example. Each step costs 15 Flightstones plus a certain number of crests. Some upgrades give discounts on Flightstones. Once an item has been upgraded to a certain amount, it can be degraded and returned to the upgrader for a lower amount of both currency types.
Many locations have upgraders for their items, including the main Island and some outposts. The NPCs offer an upgrade coupon and a chance to obtain a new recipe. The upgrade discount increases as more items are upgraded. It can be increased by having players complete certain achievements or complete quests.
Icewind Dale does not have an item upgrader at the beginning, unlike Cromwell from Baldur's gate II. Instead, the NPCs that are available to help with upgrades require various methods which is both an improvement but also a drawback.
In Season 3, several new features have been added to the upgrade system. After an upgrade has been completed to a specific level for an armor slot, upgrading other items to the same level, will cost less. This applies even if the items are from another set of equipment.
The discount applies to all accounts. The amount of Harbinger Crests required to upgrade is cut also, but is only available when certain milestones are achieved.
Crests
Players have a number of options for upgrading their gear in WoW. Flightstones are an item that is available to all players for upgrading. Crests are more specialized and are used for specific upgrades to the level of an item. Crests are an integral part of the Dragonflight Gear Progression System, which was introduced in version 10.1. They are available in four ranks.
The first thing to note is that crests are only able to be spent on gear of a specific rank, and each rank has its own requirements for its upgrade path. The simplest and most straightforward upgrade process costs just 15 crests while the most complex can require as much as 20 crests, based on the type of gear that is being upgraded.
Players can earn crests by working through tasks at the appropriate level. This could mean doing outdoor activities or completing dungeons and raids in all difficulty levels to obtain equipment of lower tier or Mythicbosses for raids, or dungeons that have a high difficulty for gear in the endgame. The crests can later be exchanged at an item upgrader NPC like Cuzolth in Dornogal or Vaskarn in Valdrakken to get the appropriate upgrade routes and steps.
Using these new currencies isn't too difficult however, the system does introduce some changes to the overall upgrade process. Once a piece of gear has reached the highest level of upgrade for any rank (Explorer or Adventurer) it no longer requires Flightstones. This change is intended to allow players to get their gear up to the highest possible ilvl on all their characters instead of relying only on seasonal loot.
Another notable change is that crests only have one purpose, so it's important to use them wisely. It is best to use your Whelpling-rank Crests on the highest-quality gear you can locate, and keep Drake and Wyrm Crests to be used for the next set of upgrades. This is especially true for items like rings and trinkets that fill multiple slots on the character, that will be able to benefit from the account-wide discount when all slots are filled with top-quality gear.