From
Raoul's Blacksmithing FAQ v1.16:
What's this I hear about weapon and armor specialization?
* When you reach 200 (and level 40) in Blacksmithing, you can 'specialize' via quest in either Armorsmith, or Weaponsmith..
"What do these do?" You ask?
* Armorsmith: Makes available extra armoring plans.
* Weaponsmith:: Makes available extra weapon plans. Further specializes (at 250 and level 45) into Axesmith, Hammersmith, or Swordsmith.