Fable II Side Quests

Simply go to the Temple of Light in Oakfield and you can make donations (via the non-glowing coffer just right of the central statue). You get morality and purity points for the cash you donate, though you have to donate at least 50 gold coins in order to earn anything. Donating more than 5,000 gold coins will earn you the same amount of morality and purity, so don't bother donating in sums larger. The best amount to donate in is 250 gold, which will earn you 10 morality points and 10 purity points. You can donate over and over again, as much or as little as you want.

After donating a significant chunk of change, you'll be asked to make a donation "when the mystical sun reaches its zenith," which is to say when the sun is at its highest point, which is to say between 12:00 PM and 1:00 PM. Wait until that time and make a donation of 10,000 gold pieces (or more!) and you'll earn the Rising Sun melee weapon. It's better than pretty much anything else you can get for 10,000 gold pieces so it's totally worth it.