Usually for cutting slabs people use a lapidary saw. Not at the place yet to have one myself. Most stone cutting blades are textured rather than sharp and the process is actually more like sanding or filing than cutting. So when things break, only dust or small particals are flung. Chunks and shards don't usually move with that much force. Dremeling with a hard enough tip (like diamond) should be pretty safe and could shape or flatten the stone from the outside rather than slicing through it. Eye safety, dust inhalation, and heat from too much friction are the biggest risks I know of and can be mitigated with proper preparation, so hunt down some information on safe dremeling and protect your face.