-If you purchase the Soulus Greatsword, you will see that it is much stronger than the Sword Of Aeons.
-The strongest swords are the Solus Greatsword (in Bowerstone North) or Avo's Tear. Solus Greatsword is stronger, but slower. Spare your sister to get Avo's Tear from the guild. Bareaver is weaker than Solus and only has flame augmentation.