Proficiency - They have to be able to perform at a masterful level.
Knowledge - they have to know what they are talking about.
That right there has to be up there near the top.
I am reminded of something I had happen to me a couple of years ago at a local indoor range.
The RSO came over to admire one of my SAA Colt .45's, as he said he had never got to handle a real Colt before.
I, being a great guy, offered to let him shoot it.
So he loaded it with 6 rounds,
and promptly shot a hole in the ceiling with it.
Seems pointing the gun straight up while cocking it, with your finger in the trigger guard, then "throwing down" on the target is not the best or safest way to shoot SAA's!
Then he chewed me out for having a "hair-trigger" gun on his range.
BTW: He was a bit of a "Range Nazi" also!
I haven't been back since!
rcmodel