This trophy is called "
A Sharper Sword" and it requires the user to upgrade a piece of equipment at the blacksmith.
Once you have access to the Guild and can travel to a capital, select Shop from the Base Menu. Select Buy and purchase an extra weapon if you haven't earned one from a Quest. Return to the Base Menu and then select Go to the Capital.
After choosing a capital to travel to, select Market followed by Blacksmith. Once given the Blacksmith Menu, choose Upgrade/Synth. Select the weapon and press the
Button twice to upgrade the weapon, unlocking the trophy.