The Water Sword is the strongest of the seven primary swords. The Prince can defeat a Brute with less than ten hits. When the Water Sword is near water, the sword glows blue. The Water Sword is the only weapon strong enough to kill the Dahaka. Like the Lion Sword and the Scorpion Sword, the Water Sword is capable of charged attacks and breaking cracked walls.
The Prince can obtain the Water Sword by activating all the nine Upgrade Pedestals. Each upgrade pedestal, once activated, sends a process through the hourglass chamber which allows one out of nine digits forming a circle to glow white. When all the life upgrades are activated and the digits forming the circle glow, the chamber opens a pit in the middle of the circle, and the Water Sword rises out.
Although the sword is available to players who've obtained all the nine life upgrades, using the Water Sword is optional. The sword is obtained once the prince kills Kaileena (the first time after activating the two towers) and returns to the throne room. The players have two options: Either they can continue to go through the side door (next to the giant hourglass) with the scorpion sword or they can take it from the pit. Since it can be obtained before even putting on the mask of wraith, it makes the prince's journey as the sand wraith much easier.
- The in-game Mask of the Wraith cinematic was rendered with the Scorpion Sword on the Prince's back, although it is possible to already be in possession of the Water Sword.