That's a "tooling hole," also known as a "locating hole."
Chris Reeve Knives buys titanium in large sheets and cuts it into rectangles about the size of the knife's handle. During manufacturing, all holes are drilled into the rectangle, which then is placed onto a fixture and held securely by locating pins through the holes.
The handle is then machined into the handle of a folding knife. At this point it becomes part of either a left- or right-handed knife, and one hole becomes part of the pivot assembly while the other is left vacant (unless it's incorporated into a graphic or inlay).
Otherwise, on a finished Chris Reeve Sebenza it has no actual function.