Reg Lindop, 72, who has run his hardware store in Hanley, Stoke-on-Trent, for 35 years, decided to give up the weapons after a chance visit to his shop by two police officers who wanted a key cut. While waiting, the officers spoke to him about the national amnesty on knives.
Mr Lindop said he began stocking 6in-blade sheath knives two years ago but was worried about what they might be used for once he had sold them.
The officers offered to take the knives on display back to the station but Mr Lindop surprised them by handing over several thousand that were stacked in a back room.
Mr Lindop said: "I was afraid that someone locally may get hurt and it would be on my conscience."