The Blacksmithing skill (3) can be used to craft Spears next to a Forge. Two Board and one Ingot are needed. At shops they sell for 50 Gold, whereas Poison Glaives sell for 100 Gold. From Blacksmithing Level 6 onwards GM Spears can be crafted with the same material, that have a longer durability than regular ones.
If at Blacksmithing Level 13 a Spear is infused with a Essence of Power, Essence of Speed or Essence of Durability, the weapon can be improved respectively to a Spear of Power, Spear of Speed or Spear of Durability.