That's due to 2 reasons:
1. There used to be asherite chain armor. VR removed it and so Ashen Bronze is now the lowest level of it.
2. The crafting system for all crafts uses a "Simple xxx" schematic as the final crafting combine for multiple tiers, and a separate "xxx basis" schematic for each tier. So while they took out the "Asherite Chain Leggings" basis (for example), they left in the "Simple Chain Leggings" schematic as it is what you will use with the Ashen Bronze Leggings, Iron Chain Leggins, etc.
Rivets are the Fasteners
