As for the first line, you assert that real weapons are expensive, unreliable, and kill unintended people. Except in a de minimis sense, none of these are true of knives. Moreover, you seem to be reasoning on the basis of the premise that future technology is not meaningfully different from current technology.
In conclusion, your comment consists entirely of wishful and uninformed thinking.
As for the first line, you assert that real weapons are expensive, unreliable, and kill unintended people. Except in a de minimis sense, none of these are true of knives. Moreover, you seem to be reasoning on the basis of the premise that future technology is not meaningfully different from current technology.
In conclusion, your comment consists entirely of wishful and uninformed thinking.