Well I'm already "on my toes" because of the bump, and noticing the box cutter type weapon. I don't think I would have taken the couple steps towards the guard to begin with. I think my focus would be the collision....and how did you get 10 feet from him so quickly? Heading to the guard? I think if he wanted to do you harm he would be on you immediately. Then just hope you can beat him down, before he does you!
When I see the blade movement in your scenario, is when I think I would act by drawing attention to the situation and make a break depending on the surroundings. Can I put something between us, a row of seats, trashcan? If not I'll defend myself in the best way that suits the "moment". There is no time for indecision
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