You can use regular nail clippers to snip the sharp tips. Try not to take too much at once as you'll hit the quick, which is painful and will make it bleed. If you do accidentally hit it, you can use flour, cornstarch, or styptic powder to stop the bleeding. Just kind of pack it into the tip. The styptic powder is the best option, and you can find it at most pet stores.

I've never heard of cauterizing toenails to shorten them, not even sure how that would even work. We have cautery sticks at our clinic we use if we hit a bad bleeder, but that's about it.