Yeah. Not illegal, but restricted for sure. If kids start murdering each other with katanas because it’s a meme on TikTok or some such bullshit, then, yes, restrict the sales of katanas until that bullshit dies down.
Except we dont… Cutting instruments are used in violent crimes as the top 5 choice of a weapon, above even rifles and assault weapons… so yes thats already happening and you dont see anyone making cutting instruments illegal or asking for background checks.