That's true, but some look more scarier that the others. Katana, as well as some similar weapons, being rather fast weapon, especially operated by some skilled user instinctively induces you to realise that you will be slashed to pieces far earlier than you realize what's going on. So I wouldn't call it a trash.
The speed of a weapon is not terribly apparent until actually witnessed in action, and *entirely* irrelevant for the primal fear of getting mauled by something sharp coming your way (which, when you get down to it, comes from primitive "reptile brain" predation avoidance instincts; virtually everything that munched on our ancestors did so by way of pointy teeth and claws).
And the intimidation value of a given weapon says nothing whatsoever of its objective quality as a killing tool - indeed in only too many cases the most frightful weapons a combatant had access to were also among the worst at actually killing people. (Which didn't necessarily matter much in mass warfare as battles were won primarily by breaking enemy morale, most of the dying happened during the ensuing pursuit.)
Objectively, though, Japanese weaponsmiths were stuck with some legitimately awful raw iron (melting down *ferrous sand* was a major source; say hi to copious amounts of silicate slag and other undesireableness) and didn't really update their metalworking techniques after about the 12th century AD so yeah. They did adapt their blade designs at least which in practice meant that by late Edo period katanas had on the average grown meaningfully shorter and lighter than before, thus better suited for peacetime carry and unarmoured targets in "civilian" contexts.
By comparison, you know that vaunted "folding" technique they're unnecessarily famed for? That's tek'nikly known as
pattern welding and had been known to smiths in western Eurasia by the last centuries BCE at which time the East Asians in general, and the somewhat backwards Japanese in particular, were still transitioning from bronze to iron... By about the 11th century AD European smiths had worked out ways to get equivalent results with less man-hours and relegated the technique to decoration; their Japanese colleagues got stuck on it, partly due to the lousy raw materials they had to work with (all that laborious folding and hammering helps drive out the worst of the slag and spreads the rest evenly thus avoiding structural weakpoints).
How do you measure a one shot one kill merely shooting at the cardboard target?
You don't, and nobody who has any idea what they're talking about claims so.
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