1. Substantially reduce the power of grade 5 Guardians.
2. Enable a path to acquire holy summoning bonds via emeralds and tournaments (not just the top 3)
As you can see from this snapshot taken from a recent battle report, players have already developed their grade 5 guardians to provide boosts upwards of 85% power to their units. This in my view dramatically disrupts the balance in the game, discouraging players from engaging in battles when their units are vastly weaker, as even grade 4 guardians that are maxed out can not attain anywhere near these boosts.
In addition, non-coiners do not currently have a path to attain grade 5 guardians, even over time (something that has existed for nearly all other features you've introduced).