Unlocking Dark Knight?

[Rbstr]

If I recall correctly you can't equip a weapon until you've started the first class quest "Way of the [class]"

You have to have the story finished up until you gain access to Ishgaurd. You don't have to do any more 3.0 stuff but you need to have access to the place to talk to the trainers/guildmasters/whatevers.