I love this ad! There is actually another version of this ad which reads differently. It says:

Of course it's impossible!
But, a few of our customers have
managed to saw through steel
cable in order to save a life.
And the knife still shaved...
Enough nonsense - It ruined
the knife. But when a little
determination and a CLIPIT(tm) get
together amazing things happen.

This ad was inspired by a letter to the SpyderCo team by a diver who had to cut his buddy free. According to Sal Glesser (founder and owner of SpyderCo):

"It was a diver sawing through a cable to save another diver tangled in the cable. He used a mariner model. They were 150 feet down. Ruined the teeth. We gave him a new one, I think we've got the old one about somewhere."

He also brought up another amazing story:

"There was a local LEO that was wearing a Police model that stopped a 9mm slug, saved his leg. Also ruined the kife."