Yeah the blessing adds additional damage over a certain number of attacks, Both the damage and number of attacks go up with every rank and there’re also ability attributes which allow you to further increase them. So instead of doing just 100 damage I can do 100 +60 blessing damage.
Then there is sacrament which adds 2 benefits.The first is more additional attack that is just added to your base damage and then there is the holy damage which acts like a second attack. So when I hit an enemy with both buffs instead of doing 100 dmg I’ll do 100 + 30 from sacrament and an additional 30 holy damage from sacrament that acts as a second attack. Then on top i’ll get the plus 60 on both attacks making a total of 270 from 100. Not to mention it’s AoE cause melee and it also procs on spells 