Durability loss
The following situations can reduce an item's durability:
Being in combat at all will cause all equipped items to gradually lose durability, regardless of whether any damage is taken or dealt.
There is a small chance with each hit by your weapon that it will lose 1 durability point.
There is a small chance with each spell cast that you will lose 1 durability point to your weapon.
There is a small chance with each hit absorbed by your armor that it will lose 1 durability point.
When you die, 10% durability is lost on all equipped items (that have a durability rating). This is 10% of maximum durability, not remaining durability. You will not lose 10% durability on death if you are killed in PvP combat by another player (if a PvP flagged guard or other NPC kills you, you still lose durability) or if your death is suicide through using an item or spell that kills you (this excludes environmental damage, such as falling) or if the death is due to an encounter's mechanic (like tanking Steelbreaker with him dying as the last member - Meltdown).
When you use the services of a Spirit Healer, you lose 25% durability on all equipped items and items in your bags, on top of the 10% durability loss on your equipped items you already lost when you died.