Sensei are encouraged to use arm protectors because during class they will practice with all their students. In getting acquainted with shinai newbies will hit sensei's unprotected arm instead of kote many times, ouch! We do not recommend beginners use additional arm protector for a number of reasons, one of them being that kote itself provides enough protection for arm and wrist. Another reason is that students would get too confortable with additional cushioning. And, its easy to forget to block kote or do from your opponent if you are not feeling pain. Yes, sometimes pain in your hand, wrist and arm are a constant reminder to block your opponents attack and protect yourself.
Do you use arm protectors? Do you feel protectors harm your technique? Share with us your experience and pics!