What city did this happen in? I would've walke away too. You can't win if you're empty handed against a dude with a knife. Especially if dude has experience or training on how to use it.
I'm taking Muay Thai and Filipino martial arts. Filipino martial arts is about using weapons in your hand. I like Filipino martial arts better because in a street a fight it's more practical. There's no referee in the streets. I didn't believe my instructor when he said you can fuck someone up with a newspaper or magazine until he rolled it up, gave me a stab in the chest with it, hit my arm, and choked me with it until I tapped out lol. Paper rolled up and condensed feels like wood when it hits you.That shit hurts! Try it for yourself. You can break ribs easily with a newspaper. Since I have a little training I would've picked up two magazines or newspapers for each hand and defended myself if it came down to it but I still would've walked away. You can never determine a fight.
If you put a newspaper or knife in my hand and you have no weapon, most likely you'll be on the ground begging for you life before you even do any real damage to me. Now you know you gotta carry a weapon with you.