The achievement is unlocked the first time you fully or partially repair a degraded weapon or other piece of equipment. You can use a repair kit or employ the services of a blacksmith. Repair kits are found as loot in chests during the prologue and elsewhere. The first blacksmith you come across is in The Corner Shop in Gorhart. Some merchants sell repair kits. More than likely, though, you will need to repair a weapon before you come across such a merchant. The closest one is Ochdran Fall, the quartermaster, in Shieldring Keep.
Weapons and armor degrade. If you open up your inventory and look at a weapon, a shield, or a piece of armor, you will see an anvil icon at the top left followed by a ratio in the form XX/YY. XX is the current state compared against the pristine item value, YY. When a weapon’s durability falls to 0, it will remain equipped until you remove or replace it. However, it will become ineffective. To restore its strength, repair it using a kit or by employing the services of a blacksmith. In the very short video below, the Twinned Souls chakrams have degraded to 1/20. Using a repair kit, they are repaired to a 10/20 condition unlocking the achievement: