Stronger medicines require the freshest possible ingredients. You can get said ingredients in the Divine Sprite Forest in the southwest of Auris Bay.
The Steel Armor Mantises and Magic Armor Mantises will drop the Sawtooth Sickle and the Magic Armor Scythe. We can use these items to strengthen the medication.
Artificial ingredients cannot compare to natural ingredients.
The Mantis Scythe in Auris is incredibly hard and sharp. It will work nicely in the potion.
Remember, just go southwest from the Auris Military Harbor, and you will reach the Divine Sprite Forest.