In order to receive a promotion, the character must, first of all, be level 40 or higher. Secondly, only Premium Accounts can receive a promotion. Finally, it will cost 20,000 gp to receive the promotion when you are ready.
The first benefit of a character promotion, is that you will receive a new name for your vocation. Druids will become Elder Druids, Sagious Clererygmens, Sorcerers will become Master Sorcerers, Savant Wizards, Knights will become Elite Knights, Conquerers, and Paladins will become Royal Paladins and Imperial Guardians.
A very valuable benefit of promotion is the reduced loss in a death. Buying Promotion will reduce the experience and skills lost in a death by 30%, unlike Blessings, this benefit will be in effect as long as you have the promoted character.
NOTE: When a promoted character loses premium, they will temperarily lose the promotion until they get premium back again.