I was wondering how to change to the assassin and not knowing that the dagger that was given to me after I complete the stout mine quest, I went and sold it.

When I found out how to become the assassin, I did not have the dagger anymore, after much searching I found it in the shop I had sold it in and got it back, I then had my ninja equip it and walked into the guild and he was turn into the assassin.

Just a little note to help out.