In reply to Hannes:
Seems so, the book I just finished suggested exactly that.
I wouldn't be overly surprised if more than a few after seeing a hole in their sheath stopped and thought for a moment if it was repairable. And maybe a hot knife could unfuzz that bit...
Personally I thought it was distasteful to suggest asking for your climbing partner with no money to pay for the damage! Being stupid isn't so bad as being stupid and a tightass.