The easiest way is to make one yourself using the Divine Ember found atop the tower past the Moonlight Butterfly.
Alternatively you can revert the Occult Club that the Mimic by Havel's Armour drops. But then your stuck with club.
To make a Divine Weapon get any weapon to +5 and give the Divine Ember to Andrei then you'll need to Green Titanite Shards. --- thank you for submitting your opinion. someone will be along to care when they get the time. - om3rta
Another way would be to get Astora's Straight Sword. You can take it with a Master Key straight out of the Asylum. Needs 14 Faith though. --- We are all Uniformly Unique. The things you own, end up owning you. -Tyler Durden
Yep you just need a wep at +5, (a regulat wep not a name'd brand wep ) and some green talcite shards --- Apparently The Warden and Hawke went on to join Revan and The Exile in their fight against The True Sith. I expect Sheppard to join them soon- Cheator13