Well, you can display whatever icon you want for a macro.
All of the icons are there.

So you could have the priest Silence icon, in a Paladin macro.
And put that on whatever keybind on the Paladin's screen.
With the Pally macro doing nothing at all.
But with the Priest macro on the same keybind.
You could name the Pallies macro whatever the keybind is, so mousing over it will tell you Control F9 (or whatever).

However, mousing over the macro won't give you information like you get for #show or #showtooltip.
And that assumes you know the icons for each of the spells, for all of your toons.