The whole thing is don't with the scale of the animation.

first thing to do is to extract your animations.

then you need to make a copy of the animation you want to use, for example fs_swordsman (which you can call fs_troll or fs_giant)

I us repacker to do this

then you need to change the scall of the new animation to 1.5 etc, i use AnimEditor to do this.

then in the 'descr_model_battle' file you need to make sure you have the scale of the new animation under the the skeleton (like elephants and horses have etc)

make sure you make a back up of the animation folder first though