Dark Souls 2 has no small amount of secrets. Without spoiling too much about these secrets, certain special weapons in the game have the ability to unlock a special power. You’ll know that a weapon is capable of performing a special ability when it says in the description: “Unleash it’s true power to…”, for example.
Given that there’s no instruction on how to trigger these special powers, we’ve decided to play around with the game and figure it out for ourselves. Here’s how you do it:
You must two-hand wield your weapon and perform a power attack of the hand it is not currently equipped in. So if you equip the weapon in your right hand, hit the L2 button.
The weapons that have this power include the Watcher Greatsword, and the Defender Greatsword. You’ll want to experiment with the controls as you acquire new boss weapons.