Subtitle: If I see a katana slice through armor like it wasn’t even there, I’m going to reach through the screen and punch you.
I can’t even tell you how many movies I’ve seen that do this. (Not reach into fictional dimensions and punch people in the face…the katana thing.) No matter what kind of sword, a generalized slashing motion always fells the opponent. It’s like armor doesn’t exist…even though they’re clearly wearing it. It bugs the hell out of me, and has done for a very long time.
Fantasy novels sometimes fall into the same trap, although usually not as badly. It’s easy to forget that armor really works — to the extent that most of the developments in weaponry throughout history (before firearms) were a direct response to variations and improvements in armor.
If you want to know what all the movies and video games are getting wrong — or maybe take a quick, informative look at what you need to get right if you’re a writer or game maker — check out this excellent post at The Emperor’s Notepad: The pursuit of realism and armor made of butter in fictional fights.
Oh yeah, before I sign off, full disclosure: I stole the line about invincible katanas from the Emperor. May his benevolence forgive me.