There is another NPC that you can talk to in FFXIV to turn in the Vouchers you’ve collected, and you can use them to purchase the Fallen Angel Wings and Wivre Horn items.

Once you’ve purchased the Diabolos Wings, you can then equip them from your fashion accessory menu. That’s all you need to know about how to get the Diabolos Wings in FFXIV Endwalker.

Here's everything you need to know about Fashion Accessories in FFXIV, including a breakdown of each one and how to get it.