you really have a few options, but my advice would be the following
Go smites
get normal smite, undead smite, axiom (DoT), and the AE, then end ability smith wrath
then go to the KoS tree and get spell crits and casting speed maxed, and get divine recovery
this makes all your dmg spells cast fast, crit, and use very little power. As a result you can chain cast them with your melee, and cast a reactive now and then soloing.
After that I'd grab the melee crits to 100% in KoS
a good 2 handed weapon would benefit your damage well, especially one with a big spread of dmg ( x-xxx) and higher delat (3+). This would complement the melee criticals, as well as your longer casting times on heals.
Shields are not that important since your avoidance is destined to be low as hell. Its nice for stats when your in a group just healing, but the benefit isn't that great compared to the dps difference.
GL little jenarie, send me another gnome chair

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- Embries/Deadone/Sierro