Does it scale poorly into late game ?
Because its not about the low scaling damage, its about getting the extra hit.
It scales poorly at any point in the game. I don’t think it’s even worth investing in if you’re getting Chaplain, but then again I don’t know how much Last Rites is boosted by Sacrament.
Thank you guys 
twentycharsandsoon
I like having 5 in the ability just to keep the effect duration the same as last rites, and also to reduce the amount I am spending on gyslotis.
my sacre is max. with arde dagger and lvl176, i got 220+ for my additional dmg.
You can say Last Rites is Sacrament with a 25% boost.
2 months 2 late, but T/y for the information-- I’ll remember it.
I’m sorry, didn’t see that this thread got necroed 
In short: Without Last Rites, Sacrament is less damage increase than Blessing and can easily be gotten via Pardoner buffs (Blessing ends early because of hit limit). So even today without the Blessing buff, it’s better to max Blessing rather than Sacrament.
If you get Last Rites however, it doesn’t count the Pardoner buff, it only counts the level learned. In this case Sacrament gives the biggest damage increase per skill point at the moment.