well before i got blocked i made like 25 accounts with 50 brutes and got 2 of them with frying pan and one of them was with shield too. so i would say it is maybe rare , but not more rare than Hypnosis, Immortal, Noodle bowle or Leek...
the Problem is that you will not be looking for just frying pan , but also Counter + Shield along with the frying pan too. so ya this Type of Brute is damn rare.
this is the only one with "Counter + Shield + Frying Pan" which i know of:
for the future could you please rename this thread to a more informative Name like "frying pan" or somthing similar.