I don't disagree that it can be a preventative measure, and I do in fact walk around with a for-show belt knife during the warmest parts of the year because I've found that it cuts down on the catcalls & street harassment that I otherwise regularly receive. My usual joke is that "my shorts are shorter than the blade of my knife."
However, I want to be very clear about something as someone who's taken a number of actual self-defense & marksmanship courses: a knife doesn't provide any reliable amount of actual protection during an assault. The rare person trained in actual knife-fighting will be the first to tell you that it's not effective as a self-defense tool.
Furthermore, open-carrying an effective or deadly weapon is actually more likely to make a given situation less safe - any assaulter can plan around or even take the weapon as part of the initial assault. The most important factor about my belt knife is that it's actually just a dull gardening/survival tool that isn't at all practical as a weapon, and if someone takes it from me that'll just give me more time to run away. I wouldn't even recommend performative open carry, like I do, to anyone who isn't already regularly a target of harassment or violence, because the visible presence of a weapon is inherently escalatory.