Before the Holy War, SemiGods had been considered to be at the very top of the world. The very definition of SemiGod was someone that far surpassed mortals, but still wasn't a God.
Ordinary powerful individuals would typically believe that this meant SemiGods were still weaker than Gods. However, there actually wasn't much foundational difference between the two. In a way, Gods were simply SemiGods who had taken a Divine Concepts. While Divine Concepts would give the Gods tremendous powers, there would also be restraints associated with this.
It could be said that there was no upper limit to the SemiGod power level. Even the Demon Princes, Demon Dukes, Undead Emperors, and so on who were at a Main God power level could technically be called SemiGods if they didn't have any divinity or Divine Concepts.