How would you see a blade being used in the kind of scenario we are talking about?

I'd have thought you'd be surrounded by metal, stone, plastic, cloth and glass. Something solid and heavy to break glass with might be an option, but maybe there are emergency hammers provided on the trains? Nowadays I try to carry a hacksaw blade, which is small, light and non-threatening, but in a subway emergency I doubt there would be enough time to actually cut metal.

I agree about the multi-tool, and I like the Juice range too - especially the CS4. It has a woodsaw and scissors, as well as all the screwdrivers and the pliers. I'd use it as a hammer in a pinch. The scissors could be useful for cutting clothing away, either to help free people who are stuck or for first aid, getting at wounds and improvising bandages, slings and splints. I can't see me doing much with the blade. I'd rather a CS4 than one of Doug's RSKs in this scenario.