the esf trunks uses 2 different models to do this, one with the sword out and one with it in, the one with teh sword out is a submodel, (it was in 1.1 anyways) if its not coded in for that character to switch models i dont think you could just make any character do it how you wanted
if you wanted to make it work in sf for a character that it wasnt coded in to do so, youd hafta assign the sword to some bones and shrink it inside the body so you cant see it and animate it to come back to normal size in the animations you wanted it to do so,
its not an easy thig to do >_>