Ancient Class Skill Book Redeem Voucher

Can be exchanged for one of the following items in the Astral Encyclopedia "Special Rewards":
Blademaster Class Skill Manual
Desperado Class Skill Book
Warlord Class Skill Book
Ranger Class Skill Book
Sage Class Skill Book
Templar Class Skill Book
Hidden Slayer Class Skill Book
Archmage Class Skill Manual
Ronin Class Skill Book
Wind Demon Class Skill Book
Holy Dragon Envoy Class Skill Book
Soul Reaper Class Skill Book
Astromancer Class Skill Book

All of the above items become non-tradable after exchange.