In their FMV apearances the Weapons from FFVII are huge. Sapphire Weapon is the size of the city of Junon, and in the FMVs they are usually portrait as dwarfing the Highwind. Distance from the camera makes it hard to tell the actual size, but it is safe to say they are all much larger than the airship.

In FFIV the Giant of Babil was extremely large (enough to house a dungeon inside), though I don't think it is bigger than Sin (once again, hard to tell due to technology restrictions.)