by blakthunder » 06 Apr 2016 04:09
Basically you'd need to make the physical model in a 3d modeling package (blender, wings3d, 3dsmax, whatever), animate it (not wings3d, but blender, maybe 3dsmax), rig it, tag it and use a script to export it to a cube 2 supported format, e.g. iqm or md5. Once you have the model ready, you'd need to create a texture (also done in the modeling package, typically) then write the configuration file for it.
For your purposes, you just need to replace the sword mesh file (I believe it's an md5 mesh) with a properly-prepared katana model. This means having tags for the handle and end of the blade, or something like that. There's not much documentation on modeling/animating for cube 2 other than looking at already existing works.