Refined Northern Lights Armor (F) is crafted with Blacksmithing in Mabinogi (armor). This page lists everything needed to make it, checked against the game as it exists today. The interactive planner lives in the Blacksmith Companion.
How to get the manual
The manual is rank 3 and survives 30 uses; every crafting attempt spends one use.
(Refined Light Armor) Blacksmith Manual Fragment: boss drops in Alby, Ciar, Rabbie, and Math dungeons plus Rabbie Phantasm.
Materials
Expect about 4 attempts per finished item (28% average progress per attempt). Per-attempt materials are consumed on every attempt; finishing materials once per item.
Each attempt uses
5× Phantasmal Ingot — crafted product, no gather/drop method exists
2× Polished Plate — crafted product, no gather/drop method exists
1× Cleansed Mage's Gem — hard mode dungeon or Rabbie Phantasm Dungeon drop
Finishing (once per item)
2× Teardrop Gem — buy from Trade Assistant Imp / Iria Trade Merchant for 35,000 Ducats
3× Awakened Strength Fragment — drops from low dungeons like Barri Basic/Coill Basic up through hardmode