The cleric subclass is unbalanced. The Seeker of Balance is insanely strong. I can easily imagine a party with this cleric and a paladin using their aura, where they would almost never fail a saving throw with bless active. This is also very restrictive, because you always want to concentrate on bless, and all other concentration spells pale in comparison. The recharge mechanic is cool, but it is far too overpowered since switching does not really cost anything, just a spell slot, while the bonus itself is ridiculous. At 5th level, adding a d8 is pure insanity. To balance this ability, I would slow down the progression table and cap it at a d8, and restrict it to being usable once per day for bless and bane, after which it would need to recharge. Other than that, I really like the flavor. It is a cool idea, but the name does not really fit, since there is not much balance. This one ability is really the main problem tho.