The Weapon Crafting System refers to a system that allows player blacksmiths to craft weapons in Sword Art Online.
Before a weapon can be crafted, the "Production" option on the pop-up window of the blacksmith's furnace must be selected, then the blacksmith needs to put the chosen metal into the furnace for the material to be sufficiently heated. The heated metal is then moved onto an anvil and the blacksmith can choose the desired weapon type via a pop-up window. The metal must then be hit with the blacksmith's hammer a certain number of times, depending on the type of weapon and the rank of the material, before the metal takes the form of the chosen weapon type. Once the manufacturing process is completed, the system assigns the appearance, which is influenced by the material used in crafting, stats and a name for the sword. The strength of the crafted weapon is proportional to the number of hits that were needed during crafting.
- Player-crafted swords are, on average, better than equivalent monster-drop weapons, though there are exceptions.
- The appraisal window shows the name of the maker of the weapon if it is player-made.
- Unlike enhancement, crafting does not have any complete failure result, as the players will always succeed in crafting a weapon. However, weapon crafting has an aspect of randomness: even if all the parameters during the crafting remain the same, the weapon's quality may still differ each time.
- Weapons may be converted into ingots and reused in crafting.
- Sword Art Online has a large diversity of weapon names and appearance, which increase with the rank of the metal used, thus weapons made from high-ranking materials are usually unique.
- In Aincrad, there is a large variety of ingots, from real ones, like iron and copper, to mythical ones, like Mithril.