I usually cary my late grandfather's pocket knife, or an opinel (French knife) I am French after all. I'd like to carry something bigger, but I am not sure if the law allows it in my country, and I do not really have the means to buy a knife at the moment.
I only carry a knife for utility work, I rely on my fists and feet for self defense.
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If knowledge is power, I, for one, feel more powerful (shudder).