How about a new status effect?
Demonblood: Makes units count as demons, but also adds +12 temporary hp.
I'm not sure if hp would be the best tradeoff, but I figured it might be a good fit since no other bless gives a max hp increase.
Got one for Air too!
Lightning Rod: Troops with this blessing will generate a "free" thunderstrike aimed with high precision at enemy forces. The more blessed troops are on the field at once, the stronger and more precise the bolt will be.
This way even otherwise worthless holy troops like flaggelants could be useful!
