Disclaimer: All this info is obsolete as of 20/7 update. See posts below for accurate info.
September 17 test: Trinkets now work, no idea when this was patched.
Made some tests with some friends today in ATH (depth 0?). We found some odd things.
Healed after every test. Some more testing is obviously needed, but this might work as an approximation.
I will rerun the fov tests at Moorcraft & Emberlight soon.
Vanaduke Fire Snakes (well this one is obviously not from ATH)
Volcanic Plate Mail + Volcanic Demo Helm (low fire resist UV) = Can't catch fire from them
Volcanic Plate Helm + Volcanic Plate Armor = Can catch fire from them
Mad Bomber Suit (low fire resist UV) + Volcanic Demo Helm (low fire resist UV) = Can't catch fire from them
Fire Trap
Volcanic Plate Mail + Volcanic Demo Helm (low fire resist UV) = Can't catch fire from the fire trap
Vog Cub Coat + Vog Cub Cap = Can catch fire from the fire trap
Vog Cub Coat + Vog Cub Cap + 2 wetstone pendants = Can catch fire from the fire trap
Volcanic Plate Helm + Volcanic Plate Armor = Can catch fire from the fire trap
Volcanic Plate Helm + Volcanic Plate Armor + 1 soaking wetstone pendant = Can catch fire from the fire trap
Volcanic Demo Helm (low fire resist UV) + 1 Soaking Wetstone = Can catch fire from them
Volcanic Demo Helm (low fire resist UV) + Heavy Demo Suit (low fire resist UV) + 1 Soaking Wetstone = Can't catch fire from them
Volcanic Demo Helm (low fire resist UV) + Heavy Demo Suit (low fire resist UV) = Can't catch fire from them
Volcanic Demo Helm (low fire resist UV) + Mad Bomber Suit (low fire resist UV) + 1 Soaking Wetstone = Can't catch fire from them
Volcanic Demo Helm (low fire resist UV) + Mad Bomber Suit (low fire resist UV) = Can't catch fire from them
Fire Pot
Volcanic Plate Helm + Volcanic Plate Armor = 5 secs, no damage
Volcanic Plate Helm + Volcanic Plate Armor + Soaking Wetstone = 5 secs, no damage
Volcanic Plate Armor + Volcanic Demo Helm (low fire resist UV) = 4 secs, no damage (note: it actually starts at 5 but goes to 4 instantly)
Volcanic Plate Armor + Volcanic Demo Helm (low fire resist UV) + Soaking Wetstone = 4 secs, no damage (note: same as above)
Fang of Vog - ATH
Volcanic Plate Helm + Volcanic Plate Armor = 4 secs, no damage (note: actually sometimes starts at 5 and goes down instantly, sometimes 4.)
Volcanic Plate Helm + Volcanic Plate Armor + Soaking Wetstone = 4 secs, no damage (note: same as above.)
Volcanic Plate Armor + Volcanic Demo Helm (low fire resist UV) = 4 secs, no damage
Volcanic Plate Armor + Volcanic Demo Helm (low fire resist UV) + Soaking Wetstone = 4 secs, no damage
Volcanic Demo Helm (low fire resist UV) + Mad Bomber Suit (low fire resist UV) + 1 Soaking Wetstone = 4 secs, no damage
Volcanic Demo Helm (low fire resist UV) + Mad Bomber Suit (low fire resist UV) = 4 secs, no damage
Fang of Vog - Emberlight
Angelic Helm + Angelic Rainment = 9 secs, 13.5 bars
Angelic Helm = 9 secs, 11 bars
Nothing = 8 secs, 9.5 bars
Nothing + Soaking Wetstone = 8 secs, 9.5 bars
Mad Bomber Suit (low fire UV) + Angelic Helm = 8 secs, 9.5 bars
Mad Bomber Suit (low fire UV) = 6 secs, 6.5 bars (Notice how here the tooltip displays negative fire resist, yet I get less damage)
Mad Bomber Suit (low fire UV) + Soaking Wetstone = 6 secs, 6.5 bars
Volcanic Plate Armor = 6 secs, 5.5 bars
Wolver coat (mid fire resist UV) +Angelic Helm = 5 sec, 4 bars
Volcanic Plate Helm + Volcanic Plate Armor = 5 sec, 3.5 bars
Volcanic Demo Helm (low fire resist UV) = 5 sec, 3.5 bars
Volcanic Plate Helm + Volcanic Plate Armor + Soaking Wetstone = 5 sec, 3.5 bars
Wolver coat (mid fire resist UV) = 5 sec, 3.5 bars
Volcanic Plate Armor + Volcanic Demo Helm (low fire resist UV) = 4 sec, 3 bars
Volcanic Plate Armor + Volcanic Demo Helm (low fire resist UV) + Soaking Wetstone = 4 sec, 3 bars
Mad Bomber Suit (low fire resist UV) + Volcanic Demo Helm (low fire resist UV) + Soaking Wetstone = 4 sec, 3 bars
Wolver coat (mid fire resist UV) + Volcanic Demo Helm (low fire resist UV) = 4 sec, 3 bars
Wolver coat (mid fire resist UV) + Volcanic Plate Helm = 4 sec, 3 bars
Wolver coat (mid fire resist UV) + Magic Hood= 4 sec, 3 bars
Fang of Vog - Terminal 23
Volcanic Plate Helm + Volcanic Plate Armor = 5 sec, 4.5 bars
Volcanic Plate Helm + Volcanic Plate Armor + Soaking Wetstone = 5 sec, 4.5 bars
Volcanic Plate Armor + Volcanic Demo Helm (low fire resist UV) = 4 sec, 4 bars
Volcanic Plate Armor + Volcanic Demo Helm (low fire resist UV) + Soaking Wetstone = 4 sec, 4 bars
Shock - ATH
Miracle Hood (mid shock resist UV) + Wyrmwood Bracelet = Immune to shock
Miracle Hood (mid shock resist UV) = Immune to shock
Shock - ALL TIER 2
Grey Feather Cowl (mid shock resist UV) = Immune
Shock - D28 Arena
No resist = Up to 11 secs
Miracle Hood (mid shock resist UV) + Wyrmwood Bracelet = 3 secs
Conclusion
UVs actually extend the bar past maximum granting immunity to certain types of fire?
And trinkets don't?
Maybe it's only for immunity so having a low UV is all you need?
You don't need a full bar for immunity? Seems like full bar + low, or half bar+medium do it.
These tests are starting to give some really fishy results.
You can be immune to certain stats without even having a full resist bar in ATH.
A UV seems to be more important than an entire trinket.
Are they working as intended?
Is the bar display for status UVs just terribly inaccurate, with medium being more than 3 bars instead of 1?
Do the enemies inflict low, medium, or high statuses and your resistance deals differently with them?