Sword mage is a unique class of this server ,i think this awesome server have only to earn if add one our two prestige class to this class to this server.
Several prestige classes already work very well with Swordmage. Divine Champion, Blackguard, Weapon Master if you don't mind waiting until rather late for your class to bloom, Knight Errant, Duelist. Assassin or Invisible Blade if you're a sneaky type of SM.
A prestige class that advances Swordmage abilities currently is not possible, barring the recoding of many of their abilities, nor is it really necessary. The class already can only advance to 20 levels, and has all its abilities and properties filled in in that time; there's little to add to it to expand it further.