Initial thoughts:
 
Undying Evil and Sign in Blood, while good cards, could be replaced with ones that have more synergy with the deck.
 
I really like Essence Harvest since you can cast it during your second main, when the creature that attacked is still buffed. You may want more as that can be an extremely effective way of killing an opponent with plenty of chump blockers.
 
Angelic Benediction is a card you should consider adding. Unless you have a Tormented Soul out your main concern will be getting past chump blockers. This would help with that, and it has exalted.
 
You may also want to take a look at the balance between Murder, Pacifism and Oblivion Ring to add another ORing or two. Pacifism and Murder only help against creatures. ORing gets rid of anything and you have no other enchantment/artifact removal.
 
Your mana curve is really low right now so unless the changes bring it up too much you probably have room to remove one more land.