Oh it will kill you!
I've seen a towing wire break and the bare end cut a slice in the steel accomodation of a tug, if that doesn't kill you then the shackle or link from the pennant will come back and cave your head in for you, not a nice way to go.
A polyprop, and or natural fibre rope can do just as much damage depending on the size of it and the strain it's under, it may not cut through steel but it will dent it and take your arms and legs off leading to death, no question about that.