Sword of the Goddess is crafted with Blacksmithing in Mabinogi (weapon). 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 1 and survives 30 uses; every crafting attempt spends one use.
Iria Treasure Hunt Event (Back to School 2011): source of record.
Materials
Expect about 10 attempts per finished item (10% average progress per attempt). Per-attempt materials are consumed on every attempt; finishing materials once per item.
Each attempt uses
10× Iron Ingot — refine from Iron Ore (common low-rank Refining output)
4× Finest Leather Strap — weaving rank 3-1 on a spinning wheel