I have to admit, that mine get clipped before they get that far, so agree, that proper toenail clippers are appropriate in that context. I actually plan to get some for Shadow as his dew claw is getting disturbingly long. I will take it back by degrees, for fear of cutting into the blood vessel. By doing it in stages, the blood vessel will retreat and I can get it back to an acceptable length.
I am fortunate that my cats have white nails, not black ones, which are a sod to clip because it is hard to check where the blood vessel is ...
Clipping back to the blood vessel tends to reduce your chance of getting close next time, as the cat will experience the sort of pain you get when you cut too close to the 'quick' on your own nail ... Owch!