Tougher than Nails
The quest is unlocked after completing the Testing... Testing... One, Two... quest.
"Speaking with folks from all corners of Hyrule, Terrako's technician has learned much about reinforcing metals. Given the right materials, she could use this knowledge to toughen Terrako's plating."
"The technician made Terrako's armor stronger than ever! Anyone who wants to knock down this sturdy little Guardian will really have their work cut out for them."