The answer to this can depend on the purpose/focus of your character & the scenario, but I think Rank 1 Monstrance is still pretty standard - the DEX boost doesn’t increase with higher ranks in the skill - and Blessing is still valuable in many situations.
My current thought on Blessing is that it makes no sense to have more ranks in it than you can deal out hits in 45sec, because no matter what the buff dies after 45sec. The damage difference would be made up by leveling the attribute. At early levels that’s a bad value proposition - like you said, it’s expensive. It’s not too long, however, before you can afford such things. I’m at level 92ish as a Cleric 2/Priest 2 going Monk and have Blessing at 10. I generally play solo, and Blessing + Sacrament yields a significant amount more damage in most situations than without.
In a support role while partying, there’s no reason not to have Blessing if your party is fighting. As a support role I’m not sure that I would have any less than 10 ranks of Blessing, and would probably max it out. It may not be much, but more is more.