Item changes that came with the patch 9.0.4 is currently work in progress. You can track latest changes on the wiki through the Recent Changes page.
Leather Set is the lowest grade armors in Rise Online.
They can be dropped from low-level creatures in Dorion, and are also sold as +1 by Armor Merchant NPCs, Marcus, Margus ve Thalia.
Crafted (and Enhanced) versions of them can be crafted with Tailoring life skill.