In the past, before the advent of anesthesia, surgery was a terrifying and painful ordeal for patients. Among the most painful procedures was lithotomy:  cutting for bladder stones.   Patients often kept their bladder stones in ornate boxes as trophies of their survival.  However, the greatest threat to these patients was not pain but infection.
Lithotomy knives we available in sharp and probe-pointed forms.  In the hands of an inexperienced operator the latter instrument might prove safer, as the probe-point is less likely to be forced out of the staff’s groove.  The latter was also useful for enlarging the prostatic incision.