I don't care for Kydex sheaths or holsters; but if I were going to carry a fixed-blade knife IWB to use as a cutting tool, unsheathing and sheathing it, I'd prefer the rigidity of Kydex. But it's late and perhaps I'm being obtuse.

If your plan is to carry it as a concealed weapon, it doesn't matter--replacing it in the sheath would be the least of your worries. Personally I carry knives to cut stuff with, and a gun for self defense.

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Oh well, what the hell.