Gear Durability, also known as just durability, is a mechanic where items will no longer increase a player's stats once it reaches zero.
Durability is reduced by getting KO'd, completing dungeons, completing fates, crafting, and gathering.
The general action Repair allows Disciples of the Hand to increase durability of gear up to 10 levels above them by 100%. This can increase durability above 100%, but gear can only be repaired when it is below 100% and requires dark matter. Grade 1 to 6 dark matter can be used to repair gear up to a level equal to its grade times 10. Grade 7 Dark Matter can be used to repair gear up to level 80, and Grade 8 Dark Matter can be used to repair gear up to level 90. Each DoH class can only repair some gear, depending on what material the gear is made from.