Have him walking tall and powerful, ala Clone Wars, at the beginning. Then, have Anakin take Dooku's red saber after the battle. At one point in the bridge battle, in which we could hopefully have some Grievous dueling Obi-Wan and Anakin, Anakin gets pushed away, and finally, just ignites Dooku's saber and throws it like a spear and hits Grievous in the chest. Grievous collapses and starts coughing while he hits the deactivate button (Basically, this just removes the need to see the last ep of Clone Wars to know why Grievous coughes). Grievous could ignite the saber and throw it out the window, then maybe grab it in space and then use it against Obi-Wan on Utapau.
Have him walking tall and powerful, ala Clone Wars, at the beginning. Then, have Anakin take Dooku's red saber after the battle. At one point in the bridge battle, in which we could hopefully have some Grievous dueling Obi-Wan and Anakin, Anakin gets pushed away, and finally, just ignites Dooku's saber and throws it like a spear and hits Grievous in the chest. Grievous collapses and starts coughing while he hits the deactivate button (Basically, this just removes the need to see the last ep of Clone Wars to know why Grievous coughes). Grievous could ignite the saber and throw it out the window, then maybe grab it in space and then use it against Obi-Wan on Utapau.