Leveling up artifact equipment will take a lot of refinement, apparently: "These artifacts will use the familiar item refinement interface; however the primary difference being that other equipment is used to refine these artifacts rather than enchantments. Basically anything that can be equipped in the 12 slots on your character sheet can be used to empower these artifact."
With Module 4 are six new level 60 artifact belts and 21 artifact weapons. The belts have a base attribute (such as strength) that can be increased from +1 all the way to +4, while artifact weapons have the potential for "the highest base damage numbers in the game." The studio said that it might expand the artifact system further if players show support for it.