Dark Heresy Second Edition
Would each arm's +10 bonus to strength tests made using the arm stack with each other when using both arms to lift something?
Best craftsmanship bionic arms provide a +10 bonus on Agility tests requiring delicate manipulation and add a +10 bonus to Strength tests using the arm. They can be also used to store small items (such as pistol ammo clips) inside concealed interior compartments within the arm.
And would these bonuses apply to a Heft test, such as when carrying a heavy, two-handed gun and needing to increase max carrying weight to avoid being Encumbered when carrying it?
Athletes are also known for their strength and can lift great weights for short periods of time. As a Free Action, a character can make a Challenging (+0) Athletics skill test to increase his carrying capability for a single encounter. For every degree of success the character achieves, his Strength is increased by 10 for the purposes of how much weight he can carry, lift, or drag (see page 248), to a maximum modified Strength of 100. Hefting can only be attempted once, and if the character fails the test, he cannot try again until the next encounter.