Tempering
An upgrade applied to gear. Achievements track weapons and Phantom Edges tempered separately, plus Level 30 milestones.
Mechanics
Tempering is an enhancement applied to equipment. The achievements name two separate targets: weapons and Phantom Edges. Tempering 10 weapons and Tempering 10 Phantom Edges are two distinct achievements, which means the two equipment types are counted apart.
Beyond the count, the achievements set a level condition on its own: upgrade a weapon to Level 30, and upgrade a Phantom Edge to Level 30. Equipment progress therefore has two dimensions — whether it has been Tempered, and what level it has reached. Level 30 is the single-item target the achievements give.
Tempering and upgrading appear as parallel conditions in the achievement text, not as two ways of describing the same action. Costs and the exact procedure are not covered by the achievement data.
Achievement
「A Tempered Ten」 — Perform Tempering on 10 weapons
「Overwhelming Force」 — Upgrade a weapon to Level 30
「Phantom Arsenal」 — Perform Tempering on 10 Phantom Edges
「Skill Over Strength」 — Upgrade a Phantom Edge to Level 30