How can you know how much service the advy provides, apart from taking frequent looks at his H/P? But I do agree with you that there should be more ways to give recommendations to an adventurer, other than the unique item one.
I would like more ways to get reccomendations but if there were you would have to get more reccomendations total to become a noble because it should take a long time to become a noble, which it does right now.