Ornate War Sword
The Ornate War Sword or Fireblade V3 is currently the most powerful pet weapon. Hail the Roaming Gnome in ToFS for details about the quest. You need the Ceremonial Wedding Sword from Nosja or Daman on Tower of Frozen Shadow Level 5 to complete the quest.
Once completed, hail your pet and click the Ornate War Sword link to have them equipped.