Demon Helmet
(Arm: 10).
It weighs 29.50 oz.
Imbuement Slots: 2
Dwarven Helmet
(Arm: 6, protection physical +2%).
It weighs 42.00 oz.
Imbuement Slots: 2
We are going use a Claw of 'The Noxius Spawn' for testing. It ALWAYS deal 200 physical base damage whenever you wear it.
With Demon Helmet Equiped:
Min. Damage: 191
Max. Damage: 195
(Around 5-9 damage reduced)
With Dwarven Helmet Equiped:
Min. Damage: 191
Max. Damage: 193
(Around 7-9 damage reduced)
Using formulas provided by tibia.wikia.com for damage reduction:
Minimum damage reduction = totalArmor * 0.475
Maximum damage reduction = totalArmor * 0.95 - 1
Demon Helmet:
Min: 4,75 / Max: 8,5
Dwarven Helmet:
Min: 2,85 / 4,7 without 2%
2% of 200 damage = 4
Min: 6,85 / 8,7
Look really close of number with the test using Claw of 'The Noxius Spawn'.
With the 2% the Dwarven Helmet gonna protect more when the hits are really stronger. Because every 100 of phsycal damage gonna convert into 98.