Don't use a furniture finish formulation, floor finish formulations already include items that provide for a higher traction finish. Adding grit is the most common solution for increasing traction; but even bothering to add grit is rare. If you do opt to add grit, look into "Interdeck No Skid" which is a marine supply grit additive. There are also marine grits meant to be mixed with your existing paints. Since lots of people tend to go barefoot on their boats, marine grit additives tend to be less abrasive (and youre feet will thank you).
What is your rise and run? Often a short run will have far more impact in determining if you will slip down the stairs.
The grip / tread tape mentioned above also has clear plastic variants. A bit more aesthetically pleasing than the black item pictured; however, any kind of adhesive backed item is gong to ruin a finish below it and have a limited lifespan (determined by the adhesive backing, the cleanliness of the step prior to application, and humidity).
Bare feet and tennis shoes tend to do well on wood stairs, it is the occasionally stocking footed person (or rarely the leather soled shoes) that are really going to give concern.
Don't use a furniture finish formulation, floor finish formulations already include items that provide for a higher traction finish. Adding grit is the most common solution for increasing traction; but even bothering to add grit is rare. If you do opt to add grit, look into "Interdeck No Skid" which is a marine supply grit additive. Since lots of people tend to go barefoot on their boats, marine grit additives tend to be small plastic spheres (which cut down on the sandpaper under my foot feeling). You'll feel it underfoot, but it's far friendlier than many commercial products (or play sand!)