Given to you by Auryen. Reward for having 200 museum displays.
You only need to have had the item in your inventory for the replica recipe to be unlocked.
"Eleidon was a holy knight of legend in Breton history. He was a sought after man for his courage and determination to set all wrongs right. In one story, it is said that he rescued a Baron's daughter from sure death at the hands of an evil warlord. For his reward, the Baron spent all of his riches to have an enchanted shield built for Eleidon. The Shield granted Eleidon the opportunity to heal his wounds." —Yagrum Bagarn, Tamrielic Lore