Re: Do multiple elemental attacks work on the same weapon?
All damage types will stack, meaning you are able to do physical, fire, cold, lightning, poison, and magical damage all at the same time.
Lets say you have a Crystal Sword with two sockets and are using your normal attack. Assuming you do not have enough strength to up your physical damage (having greater strength will add to the damage done by a physical attack), you will deal 5-15 damage with every attack.
If you socket the sword with chipped sapphire and chipped ruby you will add 1-3 cold damage and 3-4 fire damage to your attack. This means you will be doing the following with every attack:
5-15 physical damage
1-3 cold damage
3-4 fire damage.
Your total damage will be 9-22.
This means that when you hit a monster you will do anywhere from 9 damage to 15 damage, depending upon what amount of each type you do. If you roll 5 physical damage, 1 cold damage, and 3 fire damage you will do 9 damage total. If you roll 15 physical, 3 cold, and 4 fire, you will do 22 total. This is randomly decided, so you have to assume that you will tend to do closer to the average of the minimum (9) and maximum (22), or ~15.5 damage per attack.
Keep in mind that some monsters have resistances to some (or all) types of damage, and others are entirely immune to one or two types of damage (especially in late Nightmare into Hell difficulty). However, from your questions I'm assuming you're still in normal difficulty, which means that very, very few monsters will have any form of resistance and even less will have an immunity to a type of damage.
