At first I thought that I counted wrong as Knockout turns out to be the number 11. Strength. That didn't seem right at all, but after checking the cards, turns out that both Strength and Justice can be either numbers 11 or 8. It all really depends on what kind of a deck you have and what numbers are drawn on the cards.
I'm going with the cards on Wikipedia so yep, Knockout shall be Justice. Bit of a surprise but it does kinda fit. I think? I dunno. Better than Strength in my opinion.