Blurred Knives?

I don't know if there is already a thread about it , but I've watched a lot of K-Dramas where they blurred the knives and it kept bothering me. And I think they blurr tattoos sometimes as well, but I'm not sure about that.
Does somebody know why they don't show knives ??

I think they blur out things that are deemed too violent. I also know for a fact that Dramafever will blur out stuff that wasn't blurred in the original broadcast. The reason for that being liscensing rights for example. Like in Reply 1988, I was confused because the tv sets were always blurred. I thought it was intentionally part of the drama. Then one day I caught an ep somewhere else and the images were on the tv. :p

Knives being used as weapon fall under the "violence" category and would skyrocket the rating, making it impossible to air at that time -- if at all. Tattoos are considered highly offensive (you can't enter on jjimjilbangs if they're visible) and lighted cigarettes are a bad influence on young people. All of them fall under "harmful information to youths" and could get things banned or infuriate viewers and generate a lot of suing and apology demands.

Here's the site of KCSC (Korea Communications Standards Commission) and an extract:

The funny thing is, kitchen knives are perfectly fine to show unblurred x')