IF you are really looking to see exactally how much damage you can get rid of, try this : Generally in my experiance deathwatch games start with a pod. Use your servo arm(s) to rip off Sheets of plasteel from the pod, bend them into a C shape, and let your servo arm(s) hold them infront of you, whille your natural arms hold your weapons. With your int bonus to improve the cover, + TB, you will have somthing like 59 dam reduction per sheet of plasteel in basic power armor. but expect your GM to take swift vengence on you with an orbital melta torpedo centered on your forehead should you do it