Check out Hardened Armor (SR5, p. 397). It's just like the Adept powers, but does not stack with the Armor rating of worn armor.
In other words, if you're not wearing armor, you get the +4 bonus to armor, and the 2 automatic hits. If you are wearing other armor, you do not get the +4 bonus, but you still get the 2 automatic hits on Damage Resistance.