I was curious about how much defense different items have, and here are some measurements for the defense bars displayed on armors and helms (based on pixel-counting):
-The global defense bars are approximately HALF of what is displayed on the individual armor. So an armor with 8 bars of normal defense shows 4 bars on the global scale.
-The half-bar right next to the defense icon doesn't count
-Ancient Plate shows 7.18 bars on the global, which means it has a whopping 14.36 bars of defense (the display caps at 9)
-On 5* items, a Low UV is 0.71 bars; Med UV is 1.35; and High UV is 2
-I counted 4 distinct types of defense levels, which I'll call low, med, high and ultra: (heat level 10, 5* only)
Low (6.41 bars on regular display) is used on the special type defense of mixed type armors with a Normal emphasis, such as Skolver and Vog. It is also used for both the Normal and Special defense on Chaos and Mad Bomber; these two really do have lower defense
Medium (7.35 bars) is used on the normal defense of mixed type armors with a Normal emphasis. It is also used on both of the special type defenses of armors with no normal defense, like Dragon Scale.
High (7.88 bars) is used on the special type defense of mixed type armors with a Special emphasis, like Jelly and Skelly.
Ultra (9 displayed, actual 14.36 bars) is used on the normal defense for Ancient Plate.
I suspect there is a Very High that is used for the normal defense of Ironmight and Volcanic Plate, but I do not own any of those armors so I can't test this. Based on the UV bars, I suspect Max is worth about 2.6 bars of defense on the normal display. I was trying to dig up the thread testing how defense bars work, but I couldn't find it; most of the threads I found were from around when UVs added double defense or shortly after the patch. Was there any conclusive evidence on how damage reduction from defense works?
Good, but search for studies by Antistone and Kalaina Elderfall on the effects of damage resistance. You might find them interesting.