Regarding the theory about tape around the windvane, I have two things to say...
1) If there is tape there, perhaps it is this type of tape that is used throughout the entertainment industry:
Gaffers Tape. This modern example comes in several dark colors, including brown and black.
2) If I'm not mistaken, you can't really see the letters on the windvane in the photo below either. Could it have tape on it? Or was it just missing lettering? How common is it to find these antique grenades without lettering around the windvane? Can the grenade in this photo be ruled-in or ruled-out as one used on the on-screen prop(s)?
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