Pens in moment of silence

What is the significance of holding a pen or pencil during the minute of silence observed for the people killed in France?
NPR story and photographs.

The people who were killed were artists.

Thank you.

Specifically cartoonists from a magazine, where one would use a pen vs a paintbrush/spray paint/etc.

Also, “the pen,” metaphorically, means the press, free expression of ideas, etc. As contrasted with “the sword,” violence.

Might be pushing it but PEN is also the name of an organization.

I’m going with ‘The pen is mightier than the sword’

NM