Upon reaching level 1500, you will Awaken which causes your level to reset to level 1 and unlocks Prestige (https://wiki.archlightonline.com/doku.php?id=prestige&do=edit) and Feats (https://wiki.archlightonline.com/doku.php?id=feats). This also allows you to choose your specialization, which each class has 2. You can switch between the specializations freely.

You can choose your specialization at Vyktor, in the Stronghold. He is located under the stall on the left hand side.