Oh that's interesting. I've seen a lot of colored pencil artists use solvents like rubbing alcohol, baby oil (not totally sure if that becomes an archival issue though), Zest It Pencil Blend (really popular from what I've seen), odorless mineral spirits, etc, applied with a brush. I wonder if what's in the blender pen is like one of those kinds of formulas in pen-form.

Kinda wonder if the blender application helps with transfer kinda like a fixative, like will the graphite rub off less on a page lying on top of it? (I should probably just try this out myself ahah.)