Short Answer
No, main combat weapons in Crimson Desert do not have durability and will never break. You can swing your sword, hammer, or spear as much as you want without worrying about degradation.
What Does Have Durability
Gathering tools: Pickaxes for mining and Logging Axes for woodcutting degrade with use and will eventually break. Replacements are cheap and available from most vendors.
Shields: Shields lose durability when blocking attacks, especially heavy hits. A broken shield causes Kliff to stagger much more when blocking. Repair or replace shields at a blacksmith.
Why This Matters
The absence of weapon durability is a deliberate design choice by Pearl Abyss. It eliminates the tedious repair loop found in many action RPGs, letting you focus on combat rather than inventory maintenance. You will never be caught in the middle of a boss fight with a broken sword.
Tips
Carry a spare Pickaxe and Logging Axe when exploring so you do not miss gathering opportunities.
Monitor your shield's condition bar. Repair it at a blacksmith in Hernand before it breaks.
Since weapons never break, invest in Refinement upgrades without hesitation. Your weapon will last forever.