Japanese idiomatic sentences #12 with sword

“Kotesaki” is one of our body parts which is a forearm between a wrist and an elbow. 

 If you are familiar with Kendo, you may know one of their tricks to get a point by hitting an opponent’s forearm with a shinai (bamboo sword).  Then, a judge will make a call shouting “kote waza ari ippon” “Saki” means a top or tip and “kotesaki” ends up with the meaning of “superficial”.

For example, the master in the world of craftsmen scolds his pupils saying “Don’t cheat with such superficial work!” ......