The phrase "than handguns" is a comparison between two things. In this case, it means that something is considered to be safer or less dangerous than handguns.
Sentences with «than handguns»
How did a weapon designed for warfare become easier to buy than a handgun? (nytimes.com)
When he sets out, Sebastian doesn't have much at his disposal other than a handgun and a knife. (thehdroom.com)
The Globe also repeated a tweet with a video link titled «Here's what it's like to be shot with an assault rifle» that explained how an assault rifle can do far more damage than a handgun. (fortune.com)