So Wait...... Tears of the Vanquished, or Lunar Dust?
Tahriel. The best opption for you would be Talisman of Resurgence (which you have equiped) and Solace of the Fallen (N/H) or if you cant get your hands on one of those then Purrified lunar dust (60 Frost emblems) I dont think you should have mana problems if you DP twice in a fight, using Divine Illumination (2p T10 bonus needed) for the first and Avenging Wrath + Talisman of Resurgence for the second one.
I have noticed that your spell power is really low, because your gear is missing a lot of enchantments. (sry blame the armory site if this is not true here) You want to make sure that your average Holy Lights heal for at least 50% of the DpCT (damage per cast time) of the boss. That means if the boss auto hits for 10k every second and your Holy Light is 1.5 second cast you need to be putting out 15k avg Holy Lights.