Rot and repair
Every item has 10,000 points of structure. Once per day, the item looses an amount of structure, decreasing the time until the item breaks (this amount is listed in the wiki description of each item). The remaining structure is given by the condition of the item, but has no effect on the proformance of that item. For example, a brand new sword will be just as effective as a often used sword. The only way to restore structure, is through repairing that item. For each hour of work, some of the structure is restored to that item (the amount restored is also listed in the wiki descriptions of each item). Usually, items made of harder materials such as steel and iron decay more slowly then those made from softer materials such as wood. Once all 10,000 points of structure are gone, the item breaks and is no longer functional.