Adds the Giant's Knife to Fallowstone Cave and allows you to reforge it into the Biggoron's Sword. Included in Relics of Hyrule
The Giant's Knife can be found in a chest in Fallowstone Cave, which can be found during the Cursed Tribe quest for the Orcs of Largashbur. The chest requires that you go to Chillwind Depths to retrieve the key which was stolen by Falmer.
It can be used as a dagger and tempered, but its true strength comes when you go to the Skyforge with 1 corundum ingot 3 Giant's Steel ingots (found in various Falmer hives) 3 leather strips Dwarven Oil Orcish Smithing Perk