It all comes down to the person. Anyone with a knife is dangerous, even a young kid. Disarming a trained attacker with a knife would be almost impossible without getting cut.
Best thing to do is avoid the situation. Aikido training with knives teaches principals but I personally don't think they are meant for actual knife disarming.
I know everyone has an opinion on this but I can almost guarantee that if I had a knife and you tried to take disarm me, you will get cut no matter what Aikido rank or style you are.
May I add something here as I agree it does all come down to the person concerned.
The point I think which is missed is that when talking about weapons vs. unarmed is the fact that the game has changed.
Now I think that those who use weapons are as guilty as those who don't in as much as reality goes. For instance is it REAL to the person with a knife that he has now given the right to the other person to break his neck or severely damage him.
The whole attitude here seems to be 'one has a weapon and the other must try to disarm'
That's good practice but not real in the sense that it doesn't fit life circumstances. When someone in life brings out a weapon you have now entered a new game the solution of which is not fighting but is budo. Thus the reality of budo comes into play which is nothing to do with fighting.
Good Aikido teaches you this. How many weapons people understand this? How many weapons people understand that they are putting their own life in danger when they use a weapon?
Samurai learned this lesson I suspect. Hence never to draw the sword unless you really are going to use it.
I would say that a great percentage of people who threaten with knives or even guns are relying completely on fear and the apparent sense of power it gives them over an unarmed opponent. Carried away by what they could do TO the opponent yet as in life the first to complain if the opponent then does something to them.
Thus I put it to you that if your weapons training is to do with budo
then it is indeed a fine art. If on the other hand a person learns it for other reasons it is merely a path to delusion and the way of the coward.
What do you think?