Path of Exile 2's The Third Edict update will be making considerable changes to improve the basic defensive mechanic Armour.
Overview
Armour Upgraded
A Less One-Dimensional Defence
In Path of Exile 2 patch 0.3, Armour-based characters will now have a significantly improved access to modifiers that cause this mechanic to provide damage reduction for other types of Damage, allowing players to scale Armour in order to obtain mitigation against more than just Physical Hit Damage.

An example of the new modifiers on Body Armours
You can now find modifiers on pure Armour-based equipment that will apply a percentage of your total Armour towards mitigating incoming Elemental Damage Hits.
Note: be aware that Armour applying to Elemental or Chaos Damage is calculated prior to Resistances, making it significantly weaker than how it functions in Path of Exile 1.
These modifiers will calculate the sum of total Armour applying to a specific Damage type and calculate Damage mitigation using that portion of your Armour. For more information about how Armour's Damage reduction is calculated, check out our full guide on Armour's mechanics here.

An example of the new modifiers on Gloves
Improved Passive Tree Options
In addition to the new modifiers appearing on pure-Armour equipment, players will also be able to invest further into Armour's application by allocating new Passive Tree wheels and Notables in patch 0.3.

The Prism Guard Notable in 0.3
For example
Prism Guard no longer provides maximum Elemental Resistance, instead now applying a percentage of your Armour to Elemental Damage taken from Hits.

Chillproofing, a new Notable in 0.3
A player can also invest into improving mitigation against specific Damage types utilising their Armour, such as allocating the new Chillproofing Notable or the existing
Heatproofing Notable.