This task is available on the Ironfast Keep quest board M4(4).
Your objective is to get eight Spider Stingers, which can be found by bodies of dead spiders. These monsters can be found in entire Menetyre, but many of them are located in canyons on the south-east.
When you collect proper amount of stingers, bring them to Adrith Deofrit in Ironfast Keep.
A Master's Touch
A smith from Ironfast Keep M4(4) asks you for help in reforging a damaged sword. In order to do this, you have to go to smith hermit Efyr Dynnwel.
You'll find him at the high hill in the southern part of the location M4(6).
It appears that he is sick and asks you for getting three ingredients of medicine: Jottun Grist M4(7), Fennwrac Flower M4(8) and Spidersac Ichor M4(9).
When you bring him all these ingredients, he will agree to reforge the blade but he needs one more item to do this. You have to go to Hurvar's Doorsill M4(3).
Map of Hurvar's Doorsill
1 - Master's Tallow
You'll find Master's Tollew in a chest, in the north-western part of the ruins.
Bring it to the smith, who waits for you in Ironfast Keep M4(4). Thus you'll finish the task and receive mighty one-hand sword.