Pieces of Armor are items that reduce the amount of damage taken by the player by increasing a player's defense. The damage reduction is equal to half of the total defense of the armor worn, rounded up to the nearest whole number. However, the damage taken can never be reduced to less than one point. Each set of armor offers a bonus when the complete set is worn. All armor is crafted at either an Iron Anvil or a Mythril Anvil.
Defense Calculation: If a player wearing full Iron Armor (+2 for the Helmet, +2 for the Greaves, +3 for the Chainmail, and a final +2 for the set bonus which totals at +9 defense) took a hit that would normally do 12 damage, it would only inflict 7 damage (12-4.5=7.5 truncated to 7). However, if they took a hit that would normally do 4 damage, it would not negate the damage completely. Instead, the player would take one damage (As of 1.0.4).
Armor items will not grant any defense when placed in the social equip slots, although visual effects created by the armor will still occur (e.g., flames created by Molten Armor). This does not include light given off from the mining helmet. As of the 1.0.6 patch, the Molten Armor and the Meteor Armor no longer glow.
When using a female character in 1.1, the appearance of the chestplate is different, however the helmet and greaves are still the same.
All the Hardmode Helmets (From Left to Right): Melee, Ranged and MagicAll the non hardmode armors(From left to right):Cooper,Iron,Silver,Gold,Meteor,Necro,Shadow and Molten.
Set Bonus: 20% chance to not use ammo while firing a weapon.
Total: 16 Defense; 20% chance to not use ammo while firing a weapon; 12% Increased Ranged Damage.
The Hallowed Armor is crafted by using each of the new 1.1 armors (Cobalt, Mythril, Adamantite)
To craft the Hallowed 'mask' for the melee set you'd need to have all 3 of the previous armors' mentioned, helmets.
Therefore to create the Hallowed mask you'd need - Cobalt Helmet, Mythril Helmet, Adamantite Helmet + 20 souls of sight obtained by The Twins.
The Greaves and Plate Mail are crafted in the exact same way but for the plate mail you will need 20 Souls of Might obtained from The Destroyer and for the Greaves you will need 20 Souls of Fright obtained from Skeletron Prime.