If I remember right the sword trainer is in Undercity, located in the Tirisfal Glades zone. To get there take the Zeppelin outside Orgrimmar in Durotar to Tirisfal Glades. The goblins at the top of the tower will tell you which Zeppelin goes where. Once you land head south into Undercity and ask a guard where the Weapon Master is. They'll put a flag on your map showing you where he is, which is in the War Quarter I think.