Lance Of Truth by Katherine Roberts
King Arthur's secret daughter, Rhianna Pendragon, has faced mortal danger, ice-breathing dragons and dark magic to win Excalibur, the Sword of Light. But the sword is just one of four magical Lights that she must find to restore Arthur's soul to his body and bring him back to life. Now Rhianna must head into the wilds of the North, to find the second Light, the Lance of Truth, before her evil cousin Mordred claims it. But Mordred is holding her mother Guinevere captive. Can Rhianna stay true to her quest for the Lights and save the mother she's never known, before Mordred wreaks his terrible revenge? The second book in an epic fantasy series set in the Dark Ages.