Like Mooshu, you have to earn the swords from certain bosses in DS. Most of the swords will be found on bosses in The Labyrith dungeon, like the 95 dmg. ice sword and the 100 dmg. fire sword, while others are found in various places in the world.
There used to be a sword shop in the atheneum where the athames and stuff are. For some reason KI got rid of it so ill show you the lvls you need to get swords from 2 worlds(the ones that bosses drop like really high rank that is around the places drake hatchery and tree of life or jade oni)
Mooshu-Level 40 and up Dragonspyre-Lvl 45 and up.
hope it helped ~Caleb Lionhunter Lvl 43(about to become lvl 44!)~