Guide on adding a new model, animation, and creature to HoMMV

Rotation is essentially the same as bone animation. The geometry of the artifact is attached to a bone, and the bone rotates using keyframes.
If you simply place the geometry without bones or with incorrect bones, how will it start working with the old animation?
You need to attach the new geometry to the old bone. This can be done using an effect or normally in a 3D editor.