Although Leon defeated their boss, he couldn't get carried away since he only managed to do that because he made Netro nervous and not think straight. In terms of raw strength, Leon was still light-years behind Netro, but now that his replica was working on the dragon's memories, he was certain that he would become much stronger.
"My replica didn't even finish analyzing the memories of the shadowy bastard, and Netro was probably even older, but… Oh, well. I should feel happy now that I have two free sources of skills."