I'm deeply disappointed about lack of this feature in RTW. It could be one of the coolest sides of the game. Before the game release I really hoped that we would be able to enslave captured warriors because it was common in ancient times. Read ancient authors and you'll find many examples of such events! I don't understand why CA missed this feature.

In RTW we would have more opportunities of dealing with prisoners then in MTW.

1. Kill 'em all!
2. Enslave and sell. This will bring you money and extra population in cities.
3. Give them back to their faction for ransom.
4. Just get back without ransom - to improve relationships with their faction.

Also there could be option to ransom only nobles/family members and kill or enslave other prisoners.