The sword is pretty durable and pretty strong. You can swing it but it will hurt you wrist a little bit. It looks pretty much like a samurai sword maybe a little different but it works. Don't swing at anybody for it will hurt. I would say practice soft but no hardcore swinging. Oh yeah, this is my first instructable so feel free to criticize or anything like that, give feedback. The pix might not be clear considering they were taken with camera phone but you can still tell pix I think.
Step 1: Katana Handle
Use gray rods, and green connectors for the handle. White connectors up at the top for later the guard. The handle is pretty self explanatory but it could still be a bit tricky. The black little pieces on the handle, it may make holding it more comfortable but they make the sword a little more sturdier.
Step 2: The guard of the sword
The guard can be really tricky to put together. Hopefully my instructions will be enough. But if you look at the pix then I think it is pretty well put together. Connect little while rods onto the white round connectors. Put green connectors onto little white rods as shown.
Step 3: Starting the blade
At the top of the handle where the white connectors are, the tips of nine gray rods are sticking out. hook orange connectors onto those tips, put blue spacers as shown.
Step 4: The blade and some tips for it
The pix show a tip of how to make the blade and make it easier on you. On the blade, the gray part, takes three layers. Start with the middle gray piece and fallow the pix. Once you got the middle in, the rest you can do from there I think.
Step 5: Extension for handle
If you want to make the handle a little longer to resembling a samurai sword, add on. Rebuild the handle but way shorter and connect it to regular handle w/ orange connectors. If you were able to follow the instructions I laid out, then you have yourself a descent knex katana.