Ancient Alban Knight Robe (Eiler) is crafted with Tailoring in Mabinogi (robe). This page lists everything needed to make it, checked against the game as it exists today. The interactive planner lives in the Tailoring Companion.
How to get the sewing pattern
The sewing pattern is rank 1 and survives 30 uses; every crafting attempt spends one use.
Avalon Purification Missions: Take a Purification Mission from Innes in the Outskirts of Avalon and clear it with your party. Open to any character at Fledgling talent level or higher, parties of up to eight allowed
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.