How do you give weapons elemental damage? (Fire, Lightning, Dark)

Ive been playing Dark souls 2 for some time now and I was wondering how to add elemental damage to my weapon. Does anyone know how?

In order to add elemental damage to a weapon you have to unlock a series of events.

• Unlock Blacksmith McDuff in Lost Bastille
• Light the torch on the far side of the room
• reload so he is sitting at the bench.
• Get the 'Dull Ember' from the Iron Keep
• Go back to McDuff and give the ember to him

You can now interact with him to create elemental weapons. In order to create one, you must have an elemental stone to give to him. This stone will be used in the process so be careful what you choose.

Here is some info on upgrading your weapon to include elemental damage.

With reference to: LINK

At certain reinforcement levels, specific blacksmiths can ascend a weapon. There are numerous ascension paths to choose from. They can change the stat scaling of the weapon, altering its base statistics dramatically, and sometimes add an elemental damage type and/or an auxiliary effect.

The weapon must be at the required level in order to be upgraded down a specific path and some require specific Embers that can be found throughout the world.

There is a lot of types of upgrades you can make. Simply refer to the link to check them out.