Durability | Dark Souls 3 Wiki

Durability is a game mechanic in Dark Souls 3. Weapons, shields and armor will eventually break, if the player tries really really hard to do so, and will lose some of their efficiency. Broken items will not have their durability restored by resting at a bonfire, but must be repaired at the Blacksmith in Firelink Shrine or by casting the Repair sorcery.

Durability information

• At below 30% durability an item will be "at risk", and lose 30% of its attack power and damage reduction.
• At 0 durability an item will be "broken", and lose 50% of its attack power and damage reduction.
• Rings do not have durability, and cannot be broken.
• Spell Buff and Stability are not affected, even if the weapon is broken, but skills can not be used effectively, if at all.
• Equipping a broken item will be accompagnied by a shattered glass sound. Weapons and armor even have a unique texture, or shader, for their broken state. Metal will become crumpled and bent, occasionally with an effect resembling rust, while cloth will become creased with periodic stains.  
• Each connecting swing with a weapon will deplete 0.1 durability, meaning 10 hits reduces durability with 1 point. If your weapon rebounds off a shield it will lose 0.2 durability. For bows it's 0.1 durability lost with each shot.
• Durability is not directly affected when hitting walls and such, but all breakable objects, like barrels and boxes, will reduce durability. Some static objects will also deplete durability if your weapon rebounds upon hitting it.
• Broken items must be repaired at the Blacksmith or with the Repair sorcery. All other durability states (>0) can be repaired by resting at a bonfire or by using Repair Powder.
• The Blacksmith's repair cost for broken items are (durability x 10) souls for weapons, and (durability x 5) souls for armor.
• The Wood Grain Ring slows equipment degradation.

Multiplayer

• Unlike HP, FP and Estus uses, your weapon and armour durability carry over from your own world and degrade at the usual rate. Upon returning to your own world through whatever means, your items will have received more durability damage depending on whether or not you attack and take damage and will not return to the same value or be fully repaired, as with HP, FP and Estus.

Tips for breaking equipment

• Run through several areas and clear out all enemies, also hit all breakable objects on the way.
• If you are trying to break armor then let enemies hit you repeatedly.
• The wretches, imprisoned in the room you can find the Profaned Coal in Irithyll Dungeon, have an acid surge attack that will relatively quickly break your gear. Hide behind a big shield to negate most of the damage from their attacks, and swap the shield for a fresh one if needed.  Killing the spear-using wretch is advised, as he will often summon a highly damaging tornado instead of spew acid.  Staying at a distance then moving closer is a good way to trigger the acid spray.
• Summoning an opponent equipped with Acid Surge is also a fast way to go about it.
• If you must replenish your Estus before you have completely broken your equipment, take care not to sit down at the bonfire without preparations, as it will also restore durability for all equipment. Instead unequip all relevant items and drop them next to the bonfire before you rest, then pick them back up and re-equip them after you have rested.
• A time saving measure for determining how a weapon or armor piece will look when broken is to switch from an already broken item to the unbroken one.  For about 1 second, the unbroken piece will have its broken textures.  Be sure to use the reduced menu when switching so you can see it.  Screencaping might be necessary to get a good look as it does fade quickly.
• In regards to breaking equipment for fashion and aesthetic purposes rather than for increasing difficulty, the effect is most apparent with brighter metals and cloth, and is most visible on equipment with wide smooth surfaces lacking in complex geometry, such as shields, helmets, and platemail.  Very complicated equipment or equipment composed of many small parts, such as Ornsteins helmet or the Farron Chestpiece, will often have barely noticeable changes, especially to another player, and this is even more true of equipment that's model is of equipment already in poor condition, such as the masters, ragged, or Karla sets.  Metal armor in general is more noticible broken, as the texture effects how light works on its surface. 
• For those interested in wearing broken armor in combat but also on minimizing the effect this has on success, lighter equipment and equipment that already has poor absorption suffers the least from the halving effect of broken equipment.  Having broken chest piece or helmet and keeping the less noticible gauntlets and leggings whole is another tool for reducing the loss in defense while maintaining appearance, especially with chestpieces that have their own cloth that covers the pants.  Shields are generally worthless when broken, so  if choosing to use a broken shield, using a lighter broken shield is advisable, especially since the broken effect is highly visible on wooden shields.  There is no good way to compensate for the loss of damage and options when using a broken weapon, and it is generally not advised if a person is not looking for a challenge, as the visual effect is barely noticible on most weapons, especially in motion, and thoseweapons it is most visible on are the larger, slower weapons that most require high damage to be viable.

Notes

• From Software actually put some work and thought into the durability system, but with the amount of bonfires and their ability to replenish durability, along with the relative high durability for most equipmnet, very few will actually experience the effects. But I guess we're all glad that the durability system is not as fragile as it was in Dark Souls 2.
• Since the onset of the mechanic in Demon's Souls and the advent of the Scraping Spear, durability damaging attacks and techniques have been extremely common tools for players, especially invaders, to damage the experience of other players by breaking all of their equipment, requiring some expenditure of time to return to normal gameplay, rather then being used for the tactical advantages breaking equipment would have.  This is likely one of the reasons durability is in its present state.