Weaponsmith specialization

When increasing your mastery level in smithing, every additional mastery point you invest in smithing will involve choosing one of the four affinity metals, or iron, as well as a gear type between weapons and armors. This will provide you with a specialization. Doing so will unlock the upgrades that you can bestow upon gear that meets the requirements. Furthering your specialization to higher tiers means investing the point in the same combination of metals and gear. * *There is no benefit to specializing in iron-weapon or arcanite-weapon twice as there are no Tier 3 weapon upgrades for those metals currently

Weapon Upgrades
Tier 1 upgrades do not require specialization. For the benefit of having all possible weapon upgrades together, they are included in the below table.

Save DC's
When a weapon or armor calls for a saving throw, the DC is calculated as:

8 + Proficiency Bonus + Strength or Dexterity Modifier