The process of binding the Universal Core wasn't any different from binding a regular World Core.
In fact, Damien barely felt a change while he was doing it.
Sure, his Universal Law comprehension increased immensely, to the point where he felt like he could directly control the universe if he went back, but that wasn't unexpected, nor was it something that gave him immense joy.
After all, Universal Law was a contained power. It only worked under certain circumstances, and overall, it didn't have much benefit for him.
Not that he didn't want it.
Since Universal Law was a concept close to the root of existence, it was an important stepping stone for him. Later, when he reached the point he was aiming for, this comprehension would make it infinitely easier for him to overcome the final barrier.
However, that was only his feeling in the moment.