I don't think Regis was a weak ruler at all. He was simply dealt a shit hand, because his father was the Red Emperor, and inherited from him an Empire that was collapsing. To salvage the unity and keep the peace, he married an elf woman to show his "progressive" stance (even if he really wasn't).
Now, MC is actually the weaker ruler of the two, as throughout the entire game, his actions were influenced by a third-party since the beginning - which is one of my main grievances with the game; MC essentially being everyone's puppet, and incapable of making some major decisions on his own. It's either Cass or Queen whispering in his ear. But alas, those are my reservations and don't reflect the quality of the writing as is. On that note, it is a little bit ironic that he is so susceptible to outside influence, much like the father he is laughing about.