Phoenix Gloves can be found in Gold Dungeon chests after killing the Sun Spirit. They are considered the finishing touches of Phoenix armor. However, these gloves hold a secret: If they are worn in water, they morph into Obsidian Gloves.
If you wear Phoenix Gloves in water, you get the indeed very strong Obsidian Gloves. Rumor has it these were ancient and water elementals and fire elementals battle in between these powerful gloves.