The Archaic Legwear is an armor piece found in Tears of the Kingdom.
Tears of the Kingdom
"Simple, classic legwear. They're well-worn and showing their age, but they've still got a few good years left in them. It can be a bit cumbersome to have to tie the straps."
The Archaic Legwear is the very first piece of Armor that Link can find. After awaking in a cave after the prologue, Link will find the Legwear inside of a Treasure Chest.