Emboldening bond will be a really good ability for pet classes. I mean it’s good for everyone but pet classes in particular will alway have a creature in range of them for them to use the feature on themselves. I can imagine a Beastmaster using their bond with their partner along with the Archery fighting style to basically never miss.
The crazy thing is that emboldening bond stacks with Bless, meaning you can get +2d4 on your attacks/saving throws. Not only that but the bond specifies you can add the d4 once per TURN not ROUND, so there is no reason not to use it whenever you can.
I'm actually playing a Bard/Cleric with this as my cleric subclass. I'm only level 2 so i haven't decided by Bard subclass but I'm going Bard 13/Cleric 7
Having played this in game, the THEORY of having emboldened bond and bless up at the same time doesn’t really match reality at the table (at least in my experience). Sure it is a great idea but I seem to always need to use my concentration for something else besides bless, a heal or a heroism or something. I imagine this will only get worse as I get higher levels and other great options compete with bless for my concentration
In the early levels "bless stacking" I can see being useful but I agree as you level up and gain access to stronger spells, you are better off using those stronger options. The big thing is while other clerics have the choice between bless or spirit guardians, for example, a Peace cleric can still have their bless-like effect up and have Spirit Guardians up as well.
I really like this domain especially with how you can CHOOSE to do things and aren't forced so you can honestly make this character more so a frontliner if the team needs it.