If you live in or around New York City, you can swing by Jauchem &
Meeh in Brooklyn to check out their retractable short swords and
retractable knives. See under the heading "Rentals - Edged Weapons"
on the following page.
Jauchem & Meeh: Weapons Rentals
If you are far from Brooklyn, fret not, for there are several good
alternatives. One of these is to buy a retractable Tai Chi sword,
which has a telescoping blade and a relatively blunt tip. This is not
a ceremonial piece but a practice sword used in Tai Chi exercises. At
the end of the following forum discussion, you'll see that a Tai Chi
practitioner recommends his retractable swords as a way to achieve the
Cosplay Forums: Trick Swords
Among the suppliers of retractable Tai Chi swords are Wing Lam Enterprises
and Dragon Gate.
Wing Lam Enterprises: Retractable Tai Chi Straight Sword
Dragon Gate: Retractable Tai Chi Sword
If all you need is a knife-piercing effect, you can buy modestly priced
retracting knives from a costume shop.
Costumes Inc.: Theatrical Weapons: Deluxe Retractable Knife
Costumes Inc.: Theatrical Weapons: Disappearing Knife
But if your film must show impalement by sword, an inexpensive alternative
to the retractable Tai Chi sword is the trick sword, known as a "gaff",
used by fake sword swallowers. The gaff is a telescoping sword that is
included in cheap magic kits such as the following.
eBay: Sword Swallowing
eBay: Magic Sword Swallowing Illusion
eBay: Sword Swallowing Trick
For the greatest realism, you would want to film the sword not only
pushing into the victim's flesh but emerging on the other side. For this
effect, you have to shell out quite a bit more, either by purchasing
and adapting a sword-through-body magic illusion or by turning to CGI.
A basic sword-through-body kit is the following. Note that you would
have to disguise the belt, add a blood pack, and perhaps monkey with
filming speed to get the effect right.
eBay: Sword thru Waist
As an alternative to impalement, you can achieve a good hacking effect
with a fake machete that collapses sideways into the blade rather than
down toward the handle. I have seen this done on stage with a gaff
similar to the "Knife Thru Arm" device shown at the following address
(roughly in the middle of the page) and it does look very realistic.
Magic Legends: Halloween Magic
Hollywood professionals often use CGI nowadays for gory effects, but this
is typically an expensive undertaking that calls for heavy-duty software
and specially trained 3D animation artists. For example, impalement
effects in The Last Samurai were achieved with 3ds Max software.
As Girard explains, two of the sequences involve Tom Cruise
battling an army of warriors using a sword as his weapon, and one
sequence involves a Samurai warrior throwing a lance. In all three
sequences, the weapon had to be computer-generated. "For example,
when the warrior throws the lance, he impales a soldier with it,"
Girard says. "Plus, Tom is stabbing people and you can see the
sword coming out their backs. Tom's fighting choreography in
those scenes is very fast and close to the camera, and there's
little chance a practical cheat would have worked."
Autodesk: Artists blaze through photorealistic CG effects with Autodesk
3ds max software in Tom Cruise's The Last Samurai
Autodesk: 3ds Max
I have found it interesting and challenging to work on your question. If
you have any concerns about the accuracy or completeness of my research,
please advise me through a Clarification Request and give me a chance
to fully meet your needs before you rate this answer.
sword swallow gaff
sword through flesh magic trick