Forged in Flame — Michael R. Hicks

In the second book of the In Her Name: The First Empress trilogy, Keel-Tath, the child who would unite her people as foretold by an ancient prophecy, has grown to be a young warrior in the confines of the Desh-Ka temple. She has been sheltered by her old friend and mentor Ayan-Dar from the clutches of Syr-Nagath, the Dark Queen. But when Keel-Tath is forced to choose between sanctuary and her honor, she goes into exile, leaving behind a broken-hearted Ayan-Dar.

Captured and bound in chains by those who serve the Dark Queen, she is rescued from an unspeakable fate by a warrior from the shadows. Thus begins Keel-Tath's perilous journey to the ends of her war-ravaged world, through deadly wastelands and even deadlier seas, unaware that some of those she holds most dear stand ready to betray her...
 
If you're new to the In Her Name series, here is the author's recommended reading order:
 
1. The Last War Trilogy

• First Contact
• Legend Of The Sword
• Dead Soul

2. The Redemption Trilogy

• Empire
• Confederation
• Final Battle

3. The First Empress Trilogy

• From Chaos Born
• Forged In Flame
• Mistress Of The Ages

Note that The Last War and Redemption have also been published as trilogy collections.