One of the most important artifacts in all of Asgard, this mystical mirror allows the user to contact any god, no matter where he or she is. It is a serious crime for anyone to use it without Odin's permission
The Water Mirror is in the Hall of Valhalla in Asgard. It lets you communicate with the person that you want or teleport through worlds. It plays a big role in Valkyrie Profile: Lenneth and Valkyrie Profile 2: Silmeria.
Valkyrie Profile: Lenneth
The Water Mirror allows Freya and Odin to communicate with Lenneth Valkyrie during the Sacred Phase.
During Chapter 6, if following the "A" ending, Loki shows the Water Mirror to Lucian to tell him that he can communicate with Lenneth with it. Lucian does so and sends her one of Platina's earrings, hoping she can find the other. While Lucian is distracted, Loki steals the Dragon Orb that is stored nearby. He brawls with Lucian, but Loki is victorious, slays him, and secrets away the Orb.
During Chapter 7, Freya will inform Lenneth of both Lucian's death and the Dragon Orb's disappearance, and tasks Lenneth with finding the orb.
Valkyrie Profile 2: Silmeria
" With this mirror you can talk to people and carry away the things you put into it " -Alicia of Dipan -
In the story it appears at the end of Chapter 5. Alicia, Rufus, and Arngrim are trying to retrieve the stolen Dragon Orb and find it here. Alicia explains that Silmeria explained how the Water Mirror works to her, and suggests they can take Brahms and the Orb back to Midgard through it. Before they can do so, however, Hrist appears.
Hrist forges an alliance with Alicia, stating they can use the Water Mirror to travel to Lezard's alternate dimension so that they can retrieve Gungnir, as well as the souls of Silmeria and Odin. While Alicia has no desire to rescue Odin, she agrees, on the condition that Hrist release Brahms and allow Alicia to take the Dragon Orb. Freya enters, and is enraged that a human would dare negotiate with a god. She attacks, but Hrist intercepts Freya, angered that Freya would try and harm one of her Einherjar. She then uses the Dragon Orb to overwhelm Freya, granting the party enough time to escape through the Water Mirror.
After they enter Lezard's dimension, Hrist reveals she broke a piece from the Water Mirror and brought it with her. She acknowledges that they may need to return to Asgard or Midgard to resupply, and remarks that, even broken, the Water Mirror will allow it for them.