I would like to explain this sentence a little bit: Omina is not a dude who is so sure of himself, he doesn't have any overconfidence when he says 'considering equal'. He just acquired his soul, meaning he will get stronger. Compared to Agrio, who has been Legion for almost 5000 years, Omina is sure to end up stronger than him, that is what he means by considering equal; he talks about potential.