You should have no problem getting the sword if you follow these steps (there are several other times in the game where you will use the same procedure):
1. Have you hero standing at the cocoon and your DK standing at any ruin, cave, house, etc entrance (remember that your hero and DK will be some distance apart).
2. Pause the game (and do not unpause it until you are done with the last step)
3. open the cocoon and grab the sword (game is still paused)
4. click on the DK's portrait to make him the leader and enter the ruin, cave, house, etc that he is standing next to (while the game is still paused).
Both characters will now be in the ruin, cave, house, etc - you will have the sword - and you can switch back to your hero as leader and procede with the game. Try the procedure a couple of times, because it can be useful in many different situations.
Have Fun <img src="/ubbthreads/images/graemlins/up.gif" alt="" />