Game concept
Artifact Durability
The game also links it as Durability.
From the game's encyclopedia
Every Artifact has a Durability. When all Durability is lost, the Artifact is destroyed.
Durability decays over time, but can also be lost in certain events, such as Sieges and on Succession.
Durability can be restored by choosing to Reforge or Repair the Artifact.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Artifact Durability is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Every Artifact has a Durability." It is part of Artifact. The game also links it as Durability. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.