Fort Aspenwood Elementalist
Sylvari Specialty Armors,
Primordial Dragons [Drgn]
Fort Aspenwood Elementalist
Fort Aspenwood Elementalist
The Cultural Armor achievements all require you to buy a full set of Tier 1, 2, and 3. This is to prevent a person from buying Light, Medium, and Heavy Tier 1 and avoiding the cost of T3 altogether.
Look through your wardrobe for the missing piece. If you have perhaps all of tier 1 for armor weights but have never purchased a tier 1 head piece for any weights, that’d be your missing 18th item for the achievement.