It seemed these golden knights were tougher to deal with than Emery first assumed.
His water spell [Crashing Wave] might be weakened due to the existence of his dark core, but it was still a bonafide Tier 3 spell.
Therefore, one could imagine Emery's surprise when he saw those four people managed to stand still, relatively unhurt. This also made him have to give them a little credit for their prowess.
Even so, his current objective was still to give them a lesson, not outright killing them. Therefore, Emery chose to fight using only his weaker, less deadly spells.
In the meantime, all four golden knights could be seen using their [Divine Power] ability as their bodies were covered with glimmers of light. It gave them an increased capability in the speed and strength department.