Don't worry, everything's perfectly safe! I've got one of these!
Not that they're a bad idea, of course, but these things seem to have a talismanic as much as functional value to some people in the BDSM community. When Sir Master RavenLord unpacks his toybag, the very first thing to come out is the shears and they come out with a grand pronouncement that this is now Safe Play. I've seen people haul them out when they weren't even using rope! Are you planning to snip through the quarter-inch leather cuff or the steel chain there, buddy?
This is a little alarmist of me of course, because the truth is that beating restrained people is a fundamentally safe activity that's actually pretty hard to screw up. (That's not really a joke. I'm fairly sure that even among people who have no clue and no education at all, kink-related injuries or deaths are somewhere on the lightning-strike level of likelihood.) It just bothers me that I see these shears brandished as a Totem Of Safety by people who then proceed to hit their sub square on the tailbone, or make them stand with a collar tied to the wall and knees locked, or squeeze their throat shut, or any number of retarded things.
Of course, the trust placed in the Magical Scissors is nothing compared to the other safety blanket of the sex-positive world:
Again, a very very good idea. Again, just not the end of the story. They make being a big ol' slut massively, 90-something percent safer in terms of both disease and pregnancy; they do not provide 100 percent anything. And they don't do diddly for you when you go off alone with someone you don't know. Any more than "meeting in a public place" does; unless you're planning to fuck right there under the espresso machine, someone's ability to seem nice enough for 15 minutes in a coffee shop doesn't really provide a guarantee of honesty and safety.
What to do? I wouldn't stop beating or fucking just because they're unsafe; I think that even with goofy misconceptions about safety I'm more likely to get killed driving to a freaky sexual rendezvous than during it. Driving is a good metaphor, really; it's dangerous, you know it, and you do it anyway. But you don't put on a seatbelt and then go weaving willy-nilly down the road with random stomps on the pedals; you're continuously aware of and active in your safety, rather than relying on a few passive devices to do all the work.
Driving is worth it, climbing mountains is worth it, diving with sharks is worth it. Life is dangerous, and that's okay. Despite what they seem to be telling kids these days, calculated, manageable risk is no reason to stay at home with a Nerf helmet on. Just realize that there is a risk, and don't bullshit yourself or your partners about it.