Adventurer seems appropriate for relias in concept, the effect of it isn't actually useful to him. perhaps that needs replacing with something better
I was thinking perhaps is profession should have something to do with what made him so great to begin with, but that probably IS Adventurer. Adventurer might just reference how he managed to recruit so many heroes on his journey. Despite the demands they always gave... He was born a noble, but not the kind the profession would make it seem... Less whoring and gambling, more sophisticated drinking? General might be most optimal for him. Since exp for heroes is divided, the more exp the better. Maybe if there was a Soldier profession, or Knight, that gave combat bonuses to the sovereign, he would fit that quite nicely.
Although I can understand why that kind of profession wouldn't have been included in the base game. Since it really doesn't influence play style as much as getting heaps champions. Just makes you slightly better in combat, which is more of a strategic decision (research/spending money/etc) rather than a freebe before the game has even begun.
Maybe something like "Crusader" or "Expedition Leader" which gives bonuses when out leading campaigns into wild lands or enemy territory. Sort of like some kind of 'Foreign Legion, just add Relias!'.