After the last focus stone you'll be brough back to the guild where you will find it burning and in ruins. You will also be given this quest card right away, so no worries there.
Anyway, right away there is an item on the ground beside you.
On the ground you will find: 1 x Health Potion
If you go up the stairs to the upper level of the guild, on the little balcony there is an item.
- On the balcony you will find
- 1 x Resurrection Phial
If you go back down the stairs and go towards the shop, on the ground to the right of the door is an item.
- On the ground you will find
- 1 x Health Potion
Head towards the library, you'll be thrown into a cutscene... the final quest has begun.
Enter the door to the right of the guild master, this is the guild caves. Half way down the path is a dead guy, search him to find an item.
- On the corpse you will find
- 1 x Oak Longbow
Through the doors at the other end of the bridge... is the final battle. After the cutscene... fight Jack of Blades.
Kill Jack's minions until his barrier drops, then attack him directly. Once he is down to 50% of his health he will run back to his previous spot and float up into the air. Now use your bow or magic (whichever you prefer). Once Jack is dead you are given the choice of destroying the Sword of Aeons and saving your sister or sacrificing her to gain the sword.
- Beating this quest earns you
- 1 x Jack's Mask
- 26,000 gold
- 20,000 renown
If you are playing the original version of Fable your journey is complete; as soon as you choose between your sister and the sword and you'll get some closing narration and the end credits. If you wait until the credits finish the game will continue, allowing you to explore the world, complete any of the side quests you haven't yet beaten, do some fishing, level up your character, buy some houses, get married, drink, play games, get rich, etc.
If you are playing Fable: The Lost Chapters additional quests will open up after defeating Jack, starting with The Prophets of the Fire Heart. If you chose to sacrifice the Sword of Aeons you'll be able to search for an equally powerful sword instead (see The Hidden Sword).