“Moreover, various and sundry implements can be used as weapons for both murder and suicide.”
while what Avram pointed out is 100% true. Another thing to consider is that other implements are not as deadly, nor do they hurt as many people. A gun can take down a 50 people quite quickly a knife cant really and those that are stabbed are not usually as injured as with a gun. I have treated many many attempted suicides via overdose of every med you can think of. If those people had guns at home the outcomes could have been quite different