Personally I think the best buff to warpriest would be to upgrade the feats that cleric and fvs get for their favored weapon: The level 3 feat should give 3 melee and spell power, while the level 12 feat should be as follows:
Lord of Blades, Silver Flame, Undying host: +3 melee and spell power with favored weapon
Sovereign Host, Vulkoor: +2 melee and spell power and +2 base damage with favored weapon (increases as your weapon deals 1.5[w] or 2[w] etc to be 3/4 damage)
Amaunator: +2 melee and spell power and +1 insight bonus to critical threat range. (Come on, heavy maces need some love!)
As for the proposed changes to the enhancement tree:
The damage reduction 5/- is great at early levels, but could be increased, possibly add DR to later cores as well, or make it scale with level. (DR = character level)
I feel like using wis to hit/damage is counter-productive for divine might. Maybe it would open up some other build options as long as it's just that, an option, not something that you're forced to use.
The light damage with the weapon attacks seems ok, but I'll miss my spellpower that the old enhancements gave, also +2 dice of damage sounds like a lot for a melee class, especially considering they had 3d4 light damage if they crit, as their final enhancement before. I'd feel better with 1d4 light damage, increased to 1d6 for favored weapon and +3 universal spellpower for favored weapon, then +1 die and +5 universal spellpower for each enhancement after that one, with the final enhancement increasing it to double dice for 6 seconds.
Sacred Touch could use some love, maybe more PRR or more duration.
Burden of Sin should be each time you're attacked, not each time you're hit.
Light guard is OK as they have it, but the damage is low. it should be 1d6/2d6/4d6, scaling with light spellpower.
I would prefer if Divine Power didn't give wis, but instead gave between 4 and 9 STR, depending on level (3 + 1 per 5 levels). This would allow warpriests to have good str without having to itemize it. Having +4 wis would just kinda suck as you probably have a better wis item equipped.
Anything not mentioned pretty much means I agree