This has to do with a folding knife and the bolsters on the side (front and back). Some of the pre-1840 folding knives have what looks like file work but might be engraving. Any curved type of decoration would obviously be engraving but I've seen bolsters with top to bottom straight grooves and then maybe perpendicular grooves. I think needle files could be used but I'm wondering if engravers would be the better choice.
If you can imagine the front bolster. There would be three parallel grooves from top to bottom next to the scale area. Beginning at the most forward groove, there are then straight lines to the front of the bolster in a sprayed out or sunburst pattern.
If engraving tools are the correct choice- what type and size would work for such a job? Thanks.