While the katana is a formidable weapon known for its sharpness and cutting ability, it is unlikely to cut through a knight's full plate armor. Knight armor, particularly full plate armor, was designed to provide excellent protection against cutting and stabbing attacks, including those from bladed weapons like the katana.

Full plate armor consisted of multiple layers of metal plates meticulously fitted and fastened together to cover the body. It offered substantial coverage, thickness, and overlapping layers that distributed and absorbed the force of blows. The armor was designed to defend against a wide range of weapons, including swords, axes, and other melee weapons.

The katana's cutting ability, while impressive against unarmored or lightly armored opponents, would have difficulty effectively penetrating or cutting through the solid plates and reinforced joints of knight armor. The resilience, density, and thickness of the armor made it highly resistant to cutting attacks.

Instead of trying to cut through plate armor, swords like the katana were more likely to be used to target the gaps, weak points, or less protected areas of an armored opponent, such as the visor, armpits, or joints.

It's important to note that historical sword combat was not solely reliant on cutting techniques. Blunt strikes, thrusts, grappling, and the use of other weapons and techniques were employed to exploit weaknesses in armor or to incapacitate armored opponents.

If you are interested in learning about historical armor, weapons, or swordsmanship, it is advisable to consult reputable sources or seek guidance from qualified instructors or historians who can provide accurate information and guidance on the specific characteristics and usage of those weapons.

Always prioritize safety and follow the laws and regulations of your jurisdiction when considering the use of any weapon.