The damage was somewhere over the top of the route, around 5m from the end of the 30m rope.
The overall conclusion here is simple and quite obvious. In order to increase the overall safety regarding cut resistance of a given rope system, one should try to reduce the weight that is applied within the system before looking for any other solutions
1. falling hard repeatedly onto the static rope (not enough to hurt though - there's still some stretch); or2. must it have been rubbing somewhere?