The term "advisor" was something we'd thought very hard about actually. I think there isn't really an English word that accurately reflects the term Wakamiya uses - meaning-wise "right-hand-man" or "courtier" would probably be the closest, but both are very clunky translations, hence why we went with the next best option.
In essence, Wakamiya is saying that he hopes that Yukiya would be able to be something more than just a mere pageboy, and possibly somewhat of an advisor or close confidante to him in the future. Hope this helps!