Enhancement System

The Enhancement System refers to a system in Sword Art Online which allows players to strengthen a chosen weapon or armour with additional stats: sharpness, quickness, accuracy, heaviness and durability.

Mechanics
Before an item can be enhanced, the "Reinforcing" option on the pop-up window of the blacksmith's furnace must be selected and the blacksmith must then choose the desired property of the enhancement and put all gathered materials into the furnace. Once all of the materials are liquified in mere moments, the colour of the flame changes to represent the chosen property: silver for sharpness, blue for accuracy and other colours for quickness, heaviness and durability. Then, the item must be inserted into the furnace and kept there until it starts glowing. Afterwards, the item must be moved onto an anvil and hit with a blacksmith's hammer for exactly ten times, no matter the number of enhancements that have been carried out on the same item. After the first hit, the ten hits must be carried out within three minutes or the enhancement will result in an automatic failure.

Maximum Enhancement
All items that can be enhanced have a trait called "maximum enhancement attempts". This trait regulates how many enhancement attempts, whether successful or not, can be carried out on the same item. Once this limit is reached, the item becomes an «end product», meaning that it can no longer be enhanced, even if the item's enhancement level does not match the maximum attempts number. If a blacksmith attempts to enhance an end product, the item will shatter.

Materials and Success Rate
Enhancement requires a certain number of materials, which are divided into two types: base materials and additional materials. The base materials are fixed and necessary for the enhancement, while the type of additional material determines the type of enhancement and the number of the additional material affects the success rate of the enhancement. The success rate of enhancement greatly drops after the item reaches +4. A failure in enhancement may result in:
 * No change aside from the materials being consumed and the remaining attempt count decreasing.
 * The enhancement level remains the same, but the properties change.
 * The player's item loses a level of enhancement.

Naming
When an item is enhanced, +X, where X is the number of successful enhancements that have been carried out on the item, would be appended to the item's name. The breakdown of the item's enhancements can only be viewed by opening its properties window, thus, as specifying the parameters in full becomes tedious, players abbreviate them by saying the first letter of the trait after the number of such enhancements. For example, an Anneal Blade with +3 sharpness and +3 durability would be called an Anneal Blade +6 (3S3D).

Trivia

 * Weapons and armours successfully enhanced to a level that is close to the maximum attempt value of the item shine as if they are buffed.
 * The end product destruction upon an attempt to enhance it was not present in the Sword Art Online beta.