Oh hell yes, this operation is not particularly safe at all. I'd still hold it with both hands. Visibility is zero until you get the disc to pop through for the first time. Oh, and sparks will be shooting up towards you also. Wear a full face shield ($7 at Harbor Freight). It appears that Domantori is commenting on how you COULD fix your "cutting my arm up" problem without cutting the keg like the picture you posted. True, if cutting your arm up is the problem, smoothing the cut edge is definitely a solution that doesn't require opening the hole larger. However, if you want to do it anyway, go for it.