If you have a sword parented to the right hand, you pose your figure and sword and then save the pose (you can Select Subset option if you want only some body parts and the sword saved).

Now you have a sword parented to the right hand and a pose for your figure and you want to create a pose for left hand sword.

Change the parenting of the sword from right to left hand, repeat the same process posing the figure and moving the sword to the correct place, save again the pose this time with left hand pose name.

There is one step you must do, because the sword continue to be parented to the right hand when you load the sword.

With a text editor add a line in the pose in the sword prop before the channels line. You must add

smartparent rHand      for right hand pose

smartparent lHand     for left hand pose

 

Now you can load your figure, load the prop sword and the sword will move from right hand to left hand, left hand to right hand just applying the respective pose.

Stupidity also evolves!