I'd suggest taking a look at Rev. Pee Kitty's
house rules on Absorption. I think it will do what you want. One note: to add a point of damage to an attack, you'll generally want to add either 1 (for swing-damage attacks) or 2 (for thrust-damage) levels of Striking ST, for 5 or 10 character points. If you check the damage table, that's the amount of ST you need to add to increase damage by 1 point.