"It’s not broken, per se, it just doesn’t work the way we thought it works. It gives 20% of BASE damage, not of your total damage. To test this, respec and do not allocate your points. Do the same for your weapons spec, do not allocate points. Then put on gear that does not have any stats on it. This will reflect your base damage with no additive bonuses from stats, gear, or weapon spec.
Kill something with heavy on. Record damage numbers. Do the same with light. You will see you do 20% more damage with light.
Now put all your stat gear back on and allocate your points back into your primary stat and weapon skills. Do the same test. At max level you will only see maybe a 5% difference because it only adds to your 20% to your BASE damage and doesn’t factor in all the damage you get from stats and weapon perks.
In the end, this makes a pretty clear decision to wear the Heavy Armor and not bother with light. 3 times the defense in exchange for -5% damage and dodge roll is a no brainer."