Every Weapon and Armour has durability. No matter whether you crafted your weapon and armor, obtained them as a reward, or purchased them in the Shop, it can be destroyed in the combat with monsters or deleted with the rest of the items at the reset of the location. To prevent the latter, remember to recover the stuff you lost from your body after your character died.
Learn more about respawning and revival in the article “Death and Revival and Bag with the Inventory items was deleted after the death at the location”.
Open the Inventory to check the durability status of the items in the Pockets or on your character.
Repair the equipment using Hammer and improve your Weapon and Armour characteristics such as Attack, Wall Damage, Durability, etc. by the upgrade. Collect and study Scrolls to make Weapon and Armour more powerful and durable.
Learn more about Scrolls in the article “Equipment Scrolls. How to apply”.