Just as said. And a prestigious symbol for identification, derivative of medieval heraldry and ultimately traceable to actual shields used for protection on a battlefield.
The shield on the knife in the photo below is called a “Federal” shield by knife collectors, which name and shape does suggest officialdom, law enforcement, wardens, registered guides or forestry.
The only Parker gun shield I have a picture of is the oval shield shown in the second photo. It does not look quite so "Federal", but is still derivative of coats of arms and does present a broader surface for the initials of it's owner.
I wish I knew whose initials those are on my gun. I did what research I could -- local gun clubs and the now-closed in-town sporting goods store -- but could not find a trail to follow.
http://www.medievalchronicles.com/me...-and-heraldry/