There is an adage: If you don't like the answer, ask a different question. I own and have used left-handed Umnumzaan (old model), Russell K-87 CW, and Cold Steel medium TwistMaster clip point. In my mind the essential features of a single-bladed folding knife are: safey (no inadvertent cutting yourself by knife and/or lock failure; and convenience. Trying to acquire "the strongest" locking folding knife is waste effort once the lock is verified to lock. Unless one has a compelling reason for owning big, strong, folding knives that are still not close to as durable as a fixed blade at a fraction of the cost, you wind up with a folding knife that you wear with a belt sheath - or something that wears out the pocket in which it's carried.
My Umnumzaan, weighing 5.12 ounces was bought because our fire chief does not permit EMTs to carry fixed bladed knives on a call-out. The knife is strongly built, reasonably convenient to carry in my "work" outfit, and has an integral side-window breaker. I never carry it otherwise. Were fixed bladed knives allowed, the Umnumzaan would be history.
Russell's K-87 CW was bought as an everyday carry knife. After carrying it for a long while, I could no longer deny that the blade shape is not particularly useful and its locking device - I have no idea how to categorize it - is inconvenient to release. But I must admit, the Cowry X damascus blade is hell for retaining sharpness.
And now we come to my Opinel on steroids. The TwistMaster I own is essentially the same size as the Umnumzaan while weighing 2.88 ounces. In pocket it is unnoticeable. Its locking device is as simple as these things get. The entire knife has precisely four parts - grip, blade, lock ring, pivot pin (or hinge). It opens one handed were I to require the feature. Many times when using any folding knife the locking feature is unnecessary. If not twisting its locking ring to engage, the knife is also a one-handed closer. Having used the knife as an all-purpose kitchen knife, as well as everyday carry knife, for more than three years, I conclude that its lock is sufficiently convenient and sufficiently strong for everyday carry. Its weak spot, as I believe is true of all single-bladed folders, is hinge assembly's resistance to torsional stress - that is, twisting the blade or trying to use it as a pry bar. Having used it the way I would normally use an everyday carry knife, I conclude that hinge assembly strength is overrated. That's why we have fixed blades. Its grip is about as secure as can be found, especially when hands are bloody or greasy. Its blade shape is one I appreciate, but that has little to do with our topic. Its carbon steel blade is run-of-the-mill for retaining sharpness. Since sharpening is easy and quick, this is not an issue. Its hinging assembly requires zero maintenance; I have not used any lubricant or rust preventative on hinge or blade for more than three years, and I have no plan to use any in the future. The blade acquired a mottled patina within two weeks of kitchen use. No additional change. And its twist-to-lock assembly has built-in compensation for wear and tightness.
Its liability is the darn thing was egregiously overpriced when in production. Now that it's decades out of production it's egregiously overpriced as a collector's item. For the record, I bought mine on a closeout for $4.95.
I described the knife as an Opinel on steroids. I have not handled any Opinel knife long enough for a meaningful comparison beyond reporting Opinel's twist-to-lock knives appeared to be more cheaply made. But at their price, anyone could experience this simple device. Were you to find it useful, perhaps what I think of as egregiously overpriced might not be.
Hope this helps.
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