1st defeat jack then dont do anything once you got the sword just hero save , then load the game before you faced Jackofblades (you should have the sword of aeons from the hero save) then defeat him again and through the extra sword into the vortex. After defeating him go to Mazes Quaters and seach the bookcase on the right side of the room then go down the stairs and read the gravestone of the empty grave in the middle of the courtyard and you should get Avos tear.