I understand that the fall factor depends on the actual length of the rope that will absorb the energy during a fall. The longer the rope, the smaller the rigidity of the system, and thus, the smaller the forces involved.
The rigidity of the rope is, simply put, proportional to the rope Cross section, the elastic Modulus, and inversely proportional to the length of the rope. So the longer the rope, the smaller the rigidity.
I was wondering if decreasing the system rigidity by means of an additional 'spring' connected in series at the climber side would make sense. In this case, the system rigidity would be calculated as the product of rigidities divided by the sum of those (like a paralell connection of Resistors in an electrical circuit). This Spring would reduce the decceleration and therefore reduce the involved forces (special focus here on the climber and the anchorage point). Of course, this is a simplistic view.
Does it make sense? i have googled it, and found that fall arresters are used by people working at heights, but not in rock climbing. It is mentioned that they are useful when working with static ropes (ropes with very high rigidity), which makes a lot of sense.
However, I could find nothing when it comes to rock climbing. I understand that sometimes the anchorage point could be not fully reliable, and reducing the forces on it would be welcome for the sake of security.