Attached Link: E-Frontier tutorial - Digital Sleight of Hand

If you're going to do this as one long animation (rather than break it up into various scenes with different camera angles), then you need 3 sword props - one parented to the scabbard, one to the hand, and one to the victim's chest. Then you need to control the visibility of each prop until you need it. There are various ways you can do this:

• Use the scale of them item and move it from 0 to 100 on the frame you need it to become visible (set the frame before to 0), and vice versa for making it invisible;
• Use the visibility of the prop (i believe this has become animatable in later versions of Poser, but I may be wrong), again making sure you set the frame before to the alternate state, so that you get a quick transition;
  *Using the materials room and playing with the transparency settings of the prop's materials.

E-Frontier has a tutorial looking at this technique (see link) - they do it with a hat parented to a character's hand, and its head - but there's no reason why this can't be extrapolated to three items, as you wish. I scatually did a similar trick once, to create an animation of a deck of cards being dealt out onto a table. If I can find it, I'll upload the animation onto this site so you can see the finished results.

Hope this helps.

JonTheCelt