After heading back to the hollow area, talk with Philia again to get her back into the party. She will request you to help her upgrade her weapons by collecting some materials.

Follow the below route to help you get to the weapon lab.

Once you reach Deserted Weapon Testing Field and collected the ores from killing Valley Strikes. Philia will ask for a blacksmith for the weapon forge. Kirito volunteers to find a smith to help her upgrade. You are then automatically teleported to the town area.

Make sure you trip the portal at Botany Paradise Northern Section for easy access later.

Go to the smith shop to get the weapon forged. Bring the weapon back to Philia to complete this quest. Next, she will ask you to go out for a treasure hunt.