Mike is on the money.
In fact with brass, giving it a good knocking about is the only way, as a nice patina on new unblemished brass looks odd.
Look at old brass fittings;
They are covered in large and small and minute dings dents and scratches. Engraving may be half worn away, (V hard to duplicate Exactly) but if you Can pull it off, it adds a wonderful air of "Mystery" to a piece. (I love that!) Well aged and bulled back to highlight the wear areas, and you might have a winner.....(If you got the Lines Right in the first place! LOL.)