Damaged armour can be found by certain pick-pocketing monsters who digging at the digsite. If your character is equipped with good armour when attacking enemies of a higher level with their cheap runescape accounts, its higher defences can give the opponent less opportunity to do damage.
There are other less costly procedures for obtaining armour, it includes forging using the Smithing skill and repairing damaged armour. To save time, remember that farmer100 has awesome runescape accounts for sale.
Damaged armour is a member-only item, you have to repair it in a member world. So you must have a player-owned house and an armour stand built in workshop, which requires Construction at level55. Click the damaged armour in the inventory and click the armour stand. Your character will repair it automatically.