User blog comment:Icchi/Weapons incoherences/@comment-4773581-20130730213352

Iaijutsu doesn't need a katana, it's just the sword it's most commonly used with. At its absolute core, Iaijutsu is "the art of drawing, cutting, and resheathing one's sword in a single motion". Pretty much any bladed weapon could benefit from that, since it's a surprise/counter attack based on speed and reflexes. It'd just be really hard for the long and/or heavy swords to do, for obvious reasons.

Oh yeah, and it was created (somewhere between 710 and 794) long before the katana you're thinking of (dated at 1392). At that point in time they'd have been using Tachi, the precursors of the Katana. Also, he uses a freaking gun for a sheath, and guns are known for having straight barrels, not curved barrels.