Bundle of Arrowheads is crafted with Blacksmithing in Mabinogi. 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 F and survives 30 uses; every crafting attempt spends one use.
Gilmore: general shop owner in Bangor, sells them at his counter (200 gold).
Granites: general shop owner in Filia, sells them at his counter (200 gold).
Materials
Expect about 1 attempt per finished item (200% average progress per attempt). Per-attempt materials are consumed on every attempt; finishing materials once per item.
Each attempt uses
1× Iron Ingot — refine from Iron Ore (common low-rank Refining output)