When the game was launched, 1h swords could be equipped by any base class aside archer. IMC decided to make maces the default Cleric weapon by giving it MAtk as a base stat, at this point they ended the sword support for it (and for Wizard as well since it was irrelevant…). Later when Scout was added, they gave it the ability to equip it as well since the class needed an equipment for the hand slot.
Thus, only up to a certain level you can equip 1h Swords as Cleric or Wizard.
Edit - Kedoran equipment is based on pre-existing equipment, they just copied the item entry and added as a new item. I might be wrong (and the DB that has that information is down) but i think the 315 base line was released before the 270, and due that it retain the equip status for Clerics and Wizards.