Feldwyr the Blacksmith - Act 1 & Act 2 Side Quest
Location: Underground Shelter; Eastern Greilyn Jungle
Closest Portal: Eastern Greilyn Jungle
Objective: Obtain Feldwyr's Anvil, Mythril Ore & Hammer
Reward: Random Weapon
Feldwyr the Blacksmith is a Side Quest in Act 1 which begins by speaking with Feldwyr inside of the Underground Shelter. You can find the Underground Shelter east of the Eastern Greilyn Jungle Teleporter, if you continue off the path when it curves south then you'll find his cave. Use my map screenshot below if you need additional guidance.
Note: During this quest you will encounter enemies which are higher than your characters are right now (On Mercenary the enemies are 22 - 24). It is highly recommended you come back later and do this Side Quest after reaching Act 2 or when you reach The Temple of Xeria in Act 1.
After accepting this quest from Feldwyr he will open up a portion of the Underground Shelter which was previously inaccessible to you. In this new area the path will split, the northern route will lead you to the lower level side of enemies which is where you will find Feldwyr's Anvil. The other route contains Feldwyr's Mythril Ore and will be guarded by an elite Taclak Basher which will be a higher level than the enemies on the previous side.
Both Feldwyr's Anvil and Feldwyr's Mythril Ore will be given to you when you defeat the elite enemies that hold them, both elite enemies are marked with silver stars on your map and easy to find. Upon returning both of these items to Feldwyr he'll inform you that while you were gone more taclaks blew up a nearby wall and ambushed him only to steal his hammer.
Head through the newly created hole in the northern wall to find more Taclaks which are the same level as the ones you defeated for the Mythril Ore earlier. The Hammer is being held by a pair of elite Taclaks, defeat them and their comrades then return Feldwyr's Hammer to him to complete this part of the quest.
Last but not least you'll need to visit Feldwyr's brother, Fyrndolf in the town of Aman'lu for your reward. You can find Fyrndolf inside of the armor and weapon merchants in Aman'lu (pictured below). Speak with him and he'll give you a unique or set weapon and the quest will complete here.