Well, from a cultural point of view, you may well be right. From an English-language point of view, however, you would use "deserves" because "Your Excellency" is singular. If you were to use the plural "Exellencies", then it would be:Charming! I think the 3rd person singular makes more sense to use, since the whole point is to treat the person you are addressing as if he/she were too good for you to address directly and in the 2nd person. It is presumably more respectful to speak 'from a distance', pretending the person was actually not present. Am I right?
Thanks for making me welcome into the circle!