Once you have arrived in Haven and have done the first main storyline related activities the area will become explorable. Go out of the front gate and turn left. Here you will see the blacksmith. Here you must speak to Harritt. After speaking to Harritt go to the table to create either weapons or armour, if you don't have the materials available then there are crates in the forge and lootables all around Haven. Simply craft the weapon or armour and voilà! Achievement :)