The -1000c knife wins, I'll dumb it down for tl;dr
>Heat/Boiling requires energy source (i.e the sun, fire etc to get and maintain heat)
>Cold/Freezing doesnt need an energy source (i.e lack of the sun or other energy source results in freezing temperature)
>Once the 1000c knife is moved away from energy sources required to achieve that temperature its instantly lowering in temperature
>Because the -1000c knife doesn't need an energy source it remains freezing, it will still lower/highten in temperature thanks to heat from the earth and the sun, but will lose temperature slower and the 1000c knife
>the -1000c knife also has the ability to burn like the 1000c knife because when the temperature goes beyond freezing extreme temperatures become more similar
>Considering the materials, the 1000c knife won't be as solid and the metal will have weakend with less dense molecules, while the -1000c knife would have become more solid and the molecules would have become more dense
so basiically the -1000c knife has the advantage in this, not to say the 1000c will always lose. just around 99% of the time
