Well, the way I interpret aikido training (the strikes in particular, such as shomen-uchi, and tsuki) is that you are preparing yourself for a worst-case scenario: in training, somebody tsukis, or delivers shomen-uchi, with an empty hand - but the basis of those strikes is the pre-occupation with defence against weapons: knives, broken bottles maybe, etc...
While how people attack is obviously shaped by their training, if any, and what they intend to achieve in the attack - whether they're there to kill you, cut you up a bit, steal from you, scare you, whatever: The body mechanics for edged weapons tend to be very different to the sort of strikes found in aikido. Mainly because you don't need to stick a lot of force behind a knife so you don't need to ground as much. Knives let's you play the room more easily.
If you want an interesting exercise get a couple of long-sleeve shirts you don't care about and a big red marker (one that sticks a decent distance out of your fist) and go at it with some mates. No formalism, no set strikes or defences, no stop start signal.
There are some obvious dissimilarities: It's just a simulation of one context of knife use, more similar to duelling than anything else. It highlights none of the edge control issues that a knife has. It does reproduce many of the issues of distancing, timing, angle and footwork that are the main concern of messing around with sharp pointy things though. So it's still worth a gander.