I meet a difficulty attached to a model to another model on a "bone" accurate. I searched several forums but no result. I saw that many people have asked the same question but no real result see no response. Thread found :

How to attach two XNA models together?

How can I attach a model to the bone of another model?

http://stackoverflow.com/questions/11391852/attach-model-xna

But I think it is possible.

Here is my code example attached a "cube" of the hand of my player

private void draw_itemActionAttached(Model modelInUse)
    {
        Matrix[] Model1TransfoMatrix = new Matrix[this.player.Model.Bones.Count];
        this.player.Model.CopyAbsoluteBoneTransformsTo(Model1TransfoMatrix);
        foreach (ModelMesh mesh in modelInUse.Meshes)
        {
            foreach (BasicEffect effect in mesh.Effects)
            {
                Matrix model2Transform = Matrix.CreateScale(1f) * Matrix.CreateFromYawPitchRoll(0, 0, 0);

                effect.World = model2Transform * Model1TransfoMatrix[0]; //root bone index
                effect.View = arcadia.camera.View;
                effect.Projection = arcadia.camera.Projection;
            }
            mesh.Draw();
        }
    }