In The Elder Scrolls: Blades, every piece of our gear loses its durability with every fight. If it drops to zero, the items become virtually useless, losing almost all of their attack and defense values. To make sure that such a situation never surprises us during the mission or in the dungeons of Abyss, it is good to make a habit of visiting the blacksmith (Smithy) in order to repair the equipment.
However, the repair of equipment can be expensive and it can happen that after a not very fruitful visit to the random dungeons of Abyss, we will spend more on restoring our equipment to its former glory than the gold we may obtain from the dungeon run. Interestingly, the more damaged the item, the cheaper it is to repair statistically, so it is worth calculating how much durability our equipment loses and visit the smithy at the last possible moment.
We have to be careful not to spend all the cash on the construction of a new building in the city, because then we may run out of cash for repairs before the next fights. It is good to know the average price we regularly pay for repairs and always have so much gold in reserve.
As for the prices of items, they do not change with the loss of endurance points. So don't fix everything every time, and before changing the old armor into a new one, use the previous one until the end and only then sell it to the merchant.