it was tested the longsword bent so much compared to the stiff bladed katana
You better not be referring that "role call" episode where they conducted a seriously flawed test. That was a disgrace on so many levels!
What was tested? Which swords? What period was the longsword from, and what design was it based on? What "school" of design was used to make the katana? What steel was each sword made from? You can't take 1 reproduction longsword and 1 reproduction katana and test them and conclude all swords of some type is better than all swords of the other. This is absurd!
There were many longswords whose specific design was to be super stiff and punch through armor, specifically later period pieces. There are many reproduction katanas that are super stiff, and many others that are super flimsy.
This doesn't make any sense. We have to speak in generalities, unless you want to test hundreds of different swords together. In general, longswords were designed to favor the thrust. In general, katanas were used favoring the cut.