My alt character can't buy Thavnairian Scalepowder.

[Aluja89]

Date & Time: All times
Frequency: Constant
World name: Cerberus
Character name: Wrathorn Stormclaw
NPC name: Every Special Arms NPC

Class/Level: 80
Party or solo: Solo

Area and coordinates: Mor Dhona, Limsa Lominsa, Idyllshire.

Steps:
1. Get Resistance weapon quest from NPC
2. Try to get the Scalepowder
3. But it's not listed on any of the NPC's shops

[Jeeqbit]

Do you have the quest "Resistance Is (Not) Futile" active?

[Iscah]

Is this your first weapon on your alt? For the first one you need to get the powder from Rowena. It's only for repeat weapons that you buy the powder directly with tomes and I don't think it's available before you complete the quest the first time.