Call me a coward, but getting bashed in the face by a scary Russian bloke with a massive shield is not my idea of a good sporting time.
Sure, being covered by armour would appear to make professional knight fighting “safer” or at least “less likely to result in an immediate fatality.” But because your face is covered, how is anyone — least of all the referee — supposed to know if you’re already unconscious?
I prefer my brain damage in the form of drugs and alcohol, thank you very much. Apart from that – sit back and watch some action from the M-1 Medieval fighting championships. Yes, that is a thing that exists.