As best as I understand it, "heraldic" terminology is
used in identifying symbols within coat of arms, and identifying colors
and things such as that.
To say
that something is heraldic Proper is to say that it is an archetype, so
everyone knows what the object looks like. So when Graham says that no one ever
wanted to paint him "proper", in its heraldic sense, he meant, no one
wanted
to paint him for him.