Dry topic I know but I'm fascinated. Let's take Richard Neville, Earl of Warwick for an example. Could he presumably be called by three different names? What would his close friends of equal or greater status call him? What about those of equal or greater status who he wasn't close to? And his "employee" (I use that term as a generalization, it could be a secretary or lieutenant or whatever) who he was friends with? An underling who he wasn't close to? Some random messenger bringing him a parcel? Sorry for drawing it out but I guess my question is, depending on rank and familiarity, what would you call a noble who could be called by so many different titles? Would setting matter, as in during a feast or a battle? I'm sure "my lord" and "m'lord" would be thrown around in there somewhere as well, but I'm sure by now you get the gist. Thanks for the help. Feel free to move beyond the question as needed.
Okay, I'm sure others will add their thoughts but:
Close friends or equals in a private setting - either Warwick as a sign of respect for his rank or a nickname. The period is full of Richards being referred to as Dickons, Edwards being Neds, it's a way of bonding and claiming alliance in an age of complicated ties and 'networking'.
Equals or highers in formal settings - by full title, honorifics or just Warwick. Regardless of what they think of the man they acknowledge the rank he holds or it's a grave insult.
"Employee" or someone who is further down in the social scale - full title or respectful 'My Lord' type phrases at all times if they have any sense/want to stay on the right side of him.
Since most people above and below a man of status would refer to his rank rather than him personally, using Richard or a nickname was a much more intimate sign of friendship or kinship than it might seem today. He's not just a man he's the head of a family, the representative of an estate, a political entity and his power theoretically comes direct from the King. To just deal with the man and not the rank is a distinct social privilege he keeps to a small circle of trusted friends and family.
If he's a publicly active figure he may attract a public nickname that's either positive or negative but it's unlikely to be used when he's in the room. For example with Warwick he's known as Warwick the Kingmaker because he had such strong military and political command but while tavern songs might have used that name no one would have been foolish enough to refer to him like that in any room where either he or the King were present!
Of course, a man of rank's personality might mean they act unorthodoxly or allow less courteous behaviour from those around them but I hope this general overview helps.