Something worth noting about the murders in the US that use a weapon other than firearms is that these are more likely to be used in either highly personal and/or planned out attacks (spousal murders, serial killings, rapes, etc.). IOW, the person makes a deliberate emotional decision to murder someone, then they choose a weapon. Thus, the nature of the weapon is less causal in determining whether a murder will occur at all. What that means is that these are are murders that are likely to occur anyway, even without guns. However, these are the murders where guns are already not being used as much. The types of murders where gun use is the most dominant are precisely the less personal and less planned murders where the convenience of the weapon and the ease with which it can kill are more causally determining factors in whether a murder occurs at all.
This undermines lame arguments about "Well maybe we should ban knives too". Knives are used in the type of murders in which the weapon has less causal role in the decision to murder. IOW, knives don't cause the murders in which a knife happened to be used, rather anger, vengeance, and other mentally disturbed motives would have found a way and the knife is just a byproduct. In contrast, guns are used especially in contexts where the murder is not an orchestrated forgone conclusion before a weapon is even chosen. The gun plays a major causal role and without it, such murders would often not occur.
The rationale for banning a weapon is not that it happens to be used, but that it plays a causal role and without it many of the murder in which it is used would not have occurred. All the evidence points to this being true of firearms and especially handguns, while not being true for most other weapons which are usually chosen only after the decision to murder is already made and are easily swapped for other object that are just as easy to kill with (again, unlike guns which are by far more easy to kill with than any other available weapon).