For everyone saying to give RDM Magic Sword, that is a Mystic Knight's ability traditionally. I think that's the job name you're really wanting.
Edit: Also Kitru, instead of expending a trait to do that, they could just program the DEX modifying attack into the Rapier weapon type similar to how they did it with BRD and then change the tooltip to "DEX influences the attack of Rapiers and Bows." They could then expand that to include daggers for rogue/thief as well.