First off, I am assuming you are playing this at FNMs? Or is this for casual play?
A few things are jumping out at me:
1) You have a LOT of potential life gain triggers, yet only two Archangel of Thune. This essentially says, if you have two removal spells, you're hosed (outside of Elspeth). You need to up the count to 4x in the hope that you'll always have one... otherwise, you have a lot of lifegain triggers and no real end-game. That and having two more would increase the odds you can just cast a second one in response to them countering/Doom Blade-ing the first one.
2) I would swap Soulmender with Soldier of the Pantheon. It's still a one-drop, but it has more power, pro-multicolor AND it might still gain you life.
3) You have 4x Syndic of Tithes in both the MB and SB... can't really do that... Nevermind the fact that you would probably be better suited getting your extort triggers from Blind Obedience...
4) Ethereal Armor will achieve what exactly for you? You're just begging to get two-for-one'd there.
5) I'd suggest some Precinct Captains given the mono-colored nature of the deck... they can be quite the annoying threat all on their own.
6) Heliod, God of the Sun and Spear of Heliod could do well here, offering both a big, cheap beater given that you're likely going to hit 5 devotion, as many tokens as you can pay for, and a possible source of removal if push comes to shove.
7) No Nykthos, Shrine to Nyx? You're running mono-white and it offers you a way to ramp... seems silly not to include it to me.
8) If you're looking to break the bank, I think an argument could be made for Boros Reckoner being in here too
9) Brave the Elements is your best friend here... no really... they should be AT LEAST in the SB. You might look into Gods Willing too.
Anywhom, those are just what popped into my head... give us more info on what decks/what cards you're struggling against and we can go from there...