In general, knights were heavily armored and armed with a variety of weapons, including swords, maces, and lances. They were also trained to fight on horseback, which gave them an advantage in terms of mobility. Ninjas, on the other hand, were lightly armed and armored, and they relied on stealth and deception to overcome their opponents. They were also skilled in using a variety of weapons, including swords, daggers, and shuriken (throwing stars).
In a one-on-one fight, the knight would likely have the advantage due to his superior armor and weapons. However, the ninja's stealth and deception could give him an advantage if he was able to catch the knight off guard. Additionally, the environment in which the fight is taking place could also play a role, as the ninja's skills would be better suited to a dark and enclosed space, while the knight's armor and weapons would be more effective in an open field.
Ultimately, the outcome of a fight between a knight and a ninja would depend on a number of factors, and it is impossible to say for certain who would win.