Combat now has what it was missing: resistances, elemental damage and a quality for everything crafted. The new combat guide explains it all; this is the gist.
Resistances
Each piece of armour resists fire, cold, poison and energy, by its kind and its metal or leather: blood rock and demonskin resist fire well; moon and mytheril, cold; the monsters' leathers, their own. What you wear adds up and takes that percent off a Fireball's fire, a dragon's breath or a creature's poison. Armour is still what stops blows, and the guide compares each kind: plate, bone, chainmail, ringmail, studded and leather, with their protection, their weight and whether they let you move unseen.
Elemental damage
Weapons of moon, demonskin, scorpion, elfic, angelskin, mystic, evilspirit and blood rock deal part of each blow in their element, and so do several special weapons: the Axe of Fire, the Arco de Fuego, the Flame Heavy Crossbow and the demon weapons burn; the Frozen Sword and the Ice Spirit Halberd freeze; the Poison Bow poisons; the Mystic Combat Sword strikes with energy. Many creatures resist an element or are weak to another: a frost troll suffers from fire and an undead shrugs off poison. Clicking a weapon or a piece of armour now shows how its damage is split and what it resists.
Quality
What a player crafts, weapons and armour of any craft, comes out with a quality from 1 to 200 instead of plain or exceptional. The more skill, the better it tends to be: a weapon can go from -10% to +35% damage, and a piece of armour from -5 to +15 resistance points. Arms Lore adds up to 5 more.
Silver and fire
Silver weapons do +40% damage to the undead. Dragons, drakes, the phoenix and other creatures of fire are no longer immune to fire: they resist it well, but a mage now does something to them. The fire elemental, the fairies and a few bosses are still immune.
Special weapons
The DragonLance, the Wyrmslayer and the Nightbringer land their extra blow on dragons, drakes, wyrms and wyverns at last: until now it never landed. The extra blows of the Assassin's Dagger, the Prism, the talking axes and the demon weapons now count as a blow of the one who holds them. Some special weapons that hit far above the rest now have damage in line with the others, and the Phoenix Blade's flames appear beside its victim.
Metals
The dull copper and old copper guardians carry their ore at last, as the bronze, agapite, verite, rusty and rose ones do: those seven metals are not mined, they are won from their guardian. The guide says where each metal comes from.
Creatures
Creatures hit harder than before, and mounted riders (mages, dread lords, knights and elves on horseback) fight again: until now, a mounted one did not attack. The Dark Servant and the Dark Maiden by the Britain cemetery now have the strength they were given: the Dark Servant hit like Death itself. Other players' pets and summons hit as they did.