Not much of a valid question, but I just can't
resist giving my opinion!
Well, we have to look at the fact of the weapons that are in use. Also, the veterancy of the chance encounter's fighters would be a large amount of the outcome. Finally, you will have to factor in the armor. Is the knight fully armored? Is the samurai wearing chainmail? If there is chainmail, then if the weapon is not a sword, if it was maybe a flail or a mace, chainmail would not be much protection. So, you see that it is almost impossible
to compare the two.
The knight would win , obviously.