A shield will give you 1 damage absorption.
Light armour will give you 1 damage absorption.
Medium armour will give you 2 damage absorption, but a -1 penalty roll on Dexterity.
Heavy armour will give you 3 damage absorption, but a -2 penalty roll on Dexterity.
Leviathan armour, as uncommon as it is, will give you 4 absorption and -4 on Dexterity.
Small weapons such as knives and daggers do 1 damage, but can crit with Critical Hit if you roll between 18-20, doing double damage total. This includes modifiers, so it is normally more than just 2 damage. You can also dual wield these without a hit penalty.
Larger weapons such as swords, axes and maces do 2-3 damage. Dual wielding these comes at a -3 hit penalty.
Two-handed weapons do 4-5 damage, but you can not use a shield with them.
Bows do 5 damage, but leave you vulnerable to an enemy with cover.
Crossbows do 6 damage, but take longer than bows to reload.
Firearms do 7 damage, but take time to reload and may prove unreliable at bad times, especially in bad weather.