I thought it was originally this way but they implemented a delay equal to your weapon delay when you sheathe your weapon because players were exploiting it. Players would engage a target, sheathe their weapon and then re-draw their weapon immedietly to hit the target. Since when you draw your weapon, your delay is reset, 2handed jobs would end up swinging more quickly because the time it took to attack, sheathe and redraw and hit once more was overall a shorter time than the actual delay between auto-attack rounds.