I am not about to critique all the spells involved here - but I see some problems already.
1. You are considering giving the barbarian's rage to a cleric as a "domain power" ?? - No - just no.
2. The power of the darkenss domain to see in even magical darkness is unbalancing - outright. A much better and balanced power is the following.
You have darkvision at a range of 60 ft. If you have this ability at a range of less than 30 feet - it increases to 60 ft. If the character has darkvision at a range of greater that 60 ft - the range doubles. This stacks with the effects of the darkvision spell pg 190 PHB