The final quest of the A Better Engine Blade series will have players looking for a Sturdy Helixhorn to upgrade their sword to Engine Blade III. The quest can be acquired from Cid at Hammerhead Outpost after players have completed the first two steps.
Similar to Coeurl Whiskers, the Sturdy Helixhorn is only dropped from a certain type of monster known as a Duplicorn. It is an extremely rare treasure so players should not sell the treasure after acquiring it.
To find and kill Duplicorn, players need to head to Cleigne: Old Lestallum Outpost and talk to the Tipster at the diner. Tipster has a level 29 bounty hunt, The Last Spiracorns, which will ask players to defeat 2 Duplicorns and 3 Spiracorns at Lower Wennath.
Sturdy Helixhorn is not a guaranteed drop from this quest so players might have to repeat it multiple times to get one. To further increase their chances of a drop, players need to attack the Duplicorn’s head so that a Sturdy Helixhorn is dropped and not damaged during the fight.
Instead of repeating the quest multiple times (which is a good thing as it still rewards EXP and a small amount of Gil) players can also create a manual save file before fighting the enemies and continue loading that until a Duplicorn drops the Sturdy Helixhorn.
Once the Sturdy Helixhorn has been acquired, players can return to Hammerhead and talk to Cid to upgrade their Engine Blade to Engine Blade III, maxing out its damage output. Completing the quest also rewards a decent amount of EXP.