There is no contemporary thing we say like this.
We’d call someone my love or my sweet or my dear
Or if we’re being funny we might go so far as my good man
But none of these would serve as a good way to call someone
From a distance. I wonder if it was equally unlikely
At the time this was written. There’s my lord, my liege,
And perhaps this is only with royalty. Not being quite
Familiar with royal etiquette myself, perhaps one might still
Call to a king who might be in peril “My lord!”
It indicates a certain impossibility of speaking someone’s name.
It suggests to me, once again, that Horatio is not nearly so close to Hamlet
As everyone assumes. He seems, in fact, much more
Like an idealized loyal subject (albeit not of this country)
Marcellus calls him lord, too –
But he is Lord Hamlet, to him.
Marcellus calls him by his name.