How about something similar to a Dagger Pistol which was used in the 16th-17th Century.
<img src="http://i23.photobucket.com/albums/b395/goldenlab/POTC2/DaggerPistol.jpg" border="0" alt="IPB Image" />
The idea was to still have a suitable weapon for close-quarter fighting after you pulled the trigger and missed.
Or being able to equip 2 Swords simultaneously. or a Sword & a Boarding Axe.
<img src="http://i23.photobucket.com/albums/b395/goldenlab/POTC2/DaggerPistol.jpg" border="0" alt="IPB Image" />
The idea was to still have a suitable weapon for close-quarter fighting after you pulled the trigger and missed.
Or being able to equip 2 Swords simultaneously. or a Sword & a Boarding Axe.