You are responsible for injury or death caused by you, regardless of whether you’re carrying a weapon, a tool, or use your bare hand.
Not all tools are legal to carry at all times - try carrying a box-cutter through an airport and onto a commercial airplane, for instance. Or rather, DON’T do that. Really, don’t do that.
On the other hand, in many, many places in the US most people can obtain permission to legally carry guns around around.
Context matters, as does intent. If my job requires me to have a box cutter and use it, and someone jumps me on the way home and I use it as a weapon well that does not indicate intent to use it as a weapon. On the other hand, if I carry a box-cutter in my purse but have no reason to ever use it as intended as a tool then it might be argued I intended for it to be a weapon all along.
I personally know someone who did, in fact, have a length of pipe in his truck which he used on the cranium of a would-be thief who attempted to physically pull him out of the truck. He had just finished a plumbing repair, so he actually had reason to have the pipe in the truck, and the whole incident was caught on film and it was clear that he had tried to disengage/push the other guy away/otherwise attempted less than lethal resolution prior to whacking the bad guy, ruled self-defense and no penalty and no arrest for him.
As I said, context matters. If you’re in the habit of carrying around a length of lead pipe for no real reason and you get pulled over by the cops yes, there could be legal issues. If you’re a plumber, though, carrying pipe makes a lot of sense. A biker? Not so much - I know plumbers that own and ride Harleys, but not while on the job because there’s no place for all the bits and pieces they need for work on the bike.
If you’re a carpenter and carrying around a ballpeen hammer? Sure, that’s almost certainly OK, but carrying one around while you’re riding a motorcycle? I dunno… What sort of bike repair requires a ballpeen hammer and how likely is it to be so common that carrying one around all the time makes sense? Or do you have a toolbox of a complete array of bike repair tools in a saddlebag or just the hammer?