If there was one thing Lex was grateful for, it was the fact that his body being dissolved did not cause him any pain. Maybe his nerves and pain receptors were being dissolved as well, which prevented him from feeling much of anything, really.
But even so, whenever his body was reformed, he could feel it was much more powerful. For regular humans, the Nascent realm elevated their soul strength primarily, with only minor additions in other aspects. For Lex, it was completely irrelevant which aspect was strengthened, because they would all mutually strengthen one another.
But the increase in strength was just a side effect. The main change was that his body was being altered in a way that it would be able to turn into the soul state. That meant that in the future, even if his Golden core was crushed, he would not die as long as a single speck of his body remained.