Path of Exile Item Upgrades
The performance of many Path of Exile items can be improved by upgrading the performance of them. They can cause additional damage, AD or even affixes.
Sometimes, however, upgraded Common and Magic gear is beaten out by Rare-grade equipment due to their high requirements.
Armor
Armor upgrades are a form of upgrade that can be used on weapons and armor items. They increase the stats of whatever item they are connected to. Upgrades to armor are available in the world of the game and can be purchased from Blacksmiths at any bonfire. Alternately, they can be salvaged from items that have upgrade components within them by using a specialist or more powerful salvage kit.
The amount of damage an armored item or weapon is able to absorb is dependent on the extent of its upgrades. The ability to absorb damage of a piece armor will increase as it is upgraded to the maximum upgrade level. However, it's important be aware that this upgrade will increase its weight, causing it to weigh more than before.
There are several kinds of armor upgrades available in the game, and each one has distinct effects. For example, some upgrades will give the armor a certain amount of additional health points, while others will make it stronger and lighter. The name of the armor upgrade will tell you the kind of upgrade that an item will receive, as shown below.
Some of the upgrades also require magic or a hybrid technology and magic, which are identified by the "Magic" and "Hybrids" entries in the table. Additionally, some upgrades require a fee to use, and are shown by an "Charges" entry in the table below. These charges are either constantly updated or never expire based on the upgrade.
Iron Ore is the cheapest way to improve your armor. You can find it by exploring and looting small loot chests. Titanium is more expensive but it can be obtained from the smelters in Orgrimmar and Stormwind City. Certain upgrades, such as the Reforge or the Hot Potato Books can only be applied to armor pieces of the highest level. These upgrades can give significant improvements in stats and are worth the cost, especially for single-handed weapons.
The player should be aware, however, that upgrading a piece to the maximum upgrade level will increase its defense values. However, it can also reduce the speed and agility of the piece. For this reason, it is not recommended to upgrade the majority of armor pieces beyond +9, since the added defense is usually not worth the extra weight and power costs of the upgrades needed.

Weapons
Weapon upgrades allow players the ability to improve certain aspects of their weapon. For instance, an upgrade may increase the damage dealt by the shells of a shotgun or the accuracy of a rifle that snipes. Certain firearms also have enhancements that enhance their intrinsic capabilities. These include Frictionless Materials (improves stability and reduces the risk of overheating of the weapon) and Kinetic Coils (increases the velocity of projectiles for greater damage).
The majority of weapon upgrades require a whetblade. It's one of three Power Dices and a different amount Minerals and Erons. They can be obtained by doing side quests, or taking out a certain number of monsters or bosses or by contacting the Weapon Upgrade NPC in Central Flarine.
Upgrades to a weapon, equipment Set piece or Whetblade requires visiting the NPC [Armor] Boboko in Central Flarine and paying her an upgrade cost of a certain number of Bars. The higher the upgrade level, the more bars required to complete it. The cost of upgrades will be lower if you have more than one of the relevant upgrade materials.
In Chapter 2: Season 5 the way you upgrade weapon and equipment sets has changed a bit. Prior to Chapter 2: Season 5 you could upgrade your weapon or equipment by paying a certain number of Bars. You could do this until your weapon or equipment reached its maximum upgrade level, at which point the upgrades would be reset.
It's still possible, but it depends heavily on RNG. You should consider buying equipment that has minimal upgrade levels but with high base scores and stat distributions. These will then be able to give you the highest tier perks and blessings.
The majority of players will prioritize upgrades to the weapons they use most frequently to allow them to progress quicker. Players should also upgrade the weapons that their teammates use to boost their strength. For instance, Shepard should consider upgrading the M92F to unlock the Beretta M93R, which will increase its utility when accompanied by biotic specialists like Grunt and Tali.
Jewels
Jewels are utilized in the sockets of armor and weapons, enhancing a stat and providing secondary effects. Jewelry crafting is a method of making them, where you combine a gemstone with a number specific reagents on a jewelry table. The higher the grade of the jewel the better the secondary effect. These reagents can be obtained around the world through Treasure Goblins, World Bosses and, sometimes, by salvaging Legendary gear. You can also purchase them from The Jeweler for gold and a Scattered Prism.
The Jeweler can improve the quality of gemstones in stages ranging from Crude up to Royal. Depending on the tier of the gem it can provide different stat boosts when inserted into weapons, gear and jewelry.
All kinds of jewels can be made at the Jeweler, with the exception of the rare and legendary jewels which require you to be at a sufficient level to be able to get these. Jewels can be substituted with another jewel without destroying the original. You are able to replace the jewel only once in a piece of equipment.
Utilizing more jewels in a move will make it feel smoother and is usually used to enhance the aesthetics of the movement. The jewels also improve performance and create a harder surface than steel, so that the repeated friction from pivots do not ca us e damage to the movement.
In addition to the upgrades mentioned above players can also acquire glyphs for their shields and weapons from a Glyphmaster. They offer a small benefit and can be swapped freely however they aren't guaranteed to drop as loot. Glyphs are like jewelry and can be upgraded at the Jeweler in exchange for Scattered Crystals and gold. Glyphs may also be removed and returned to the inventory. Other upgrade components such as traits or aegis cannot be swapped, and can only be found with an Upgrade extractor, or salvaging with Black Lion Salvage Kit or Ascended Salvage.
Trinkets
Trinkets are small pieces of equipment that offer a wide range of tiny but valuable benefits to your hero. They can be acquired starting in the areas of starting as loot or personal story rewards from vendors, and by doing road interactions. They can also be found on the Trading Post, or crafted by jewelers.
The first trinkets a player is able to unlock is the cloak, which grants a small, but valuable boost to movement speed and the ability to escape. The player can then collect necklaces, rings, and amulets in a similar fashion to how they acquired weapons and armor. Each piece of equipment comes with one upgrade slot that accepts either a universal or a jewel upgrade. Universal upgrades offer fewer benefits and can be put into any type of equipment while jewelry cannot be changed or upgraded and only works with specific types of trinkets.
These trinkets also provide additional bonuses and abilities that are active when the hero is not in combat. This lets a hero be more efficient while inactive. It can also make up for the lack of a strong slot in the talent tree or team that are normally filled by the hero's best stats.
A good guideline for trinket upgrades is to prioritize BiS (Best-in-Slot) items that you aren't planning to replace in the near future, then any items with desirable stats that are less important than the iLevel of the item being upgraded. This is especially true when an item has multiple stats you wish to upgrade, since it's generally better to upgrade just one important stat rather than two sub-optimal ones.
Jungle players usually upgrade their yellow trinket to a red trinket at the beginning of the game. Top and mid players, on the other hand will pick a pink or green ward, based on the matchup. These choices will have a major impact on the hero's ability to control his map.
Apart from the things mentioned above, players can discover a variety of other trinkets throughout the game in the form of trophies and awards. These can be obtained through completing certain milestones within the story. For instance, finishing the main quest of a chapter or defeating a boss. These achievements can be seen by selecting the relevant achievement from the reward tab of the hero menu.