It's good Raphtalia got a decent sword. After all, the situation in the other world is kind of irreparable: The heroes should have been a team, each with their own function in the team, but since Naofumi got kicked out, he had to work on his own, lacking offensive capability and thus being in a bit of trouble. Raphtalia is thus handling the job real heroes should have otherwise handled. If she has got a heroic weapon, she can finally do it fully.