I'm not familiar with Pawn but I'm sure there should be someone in this community who can write a script that creates a special group of players, which excludes them from being autobanned when they have forbidden weapons. So when an admin makes an event, he can add players to that group, and all those players have some amount of exclusive rights and they all can enjoy the event without getting banned.
But now I'm thinking of it, who am I talking to and what the hell do I know 
Such script actually works
The problem happens when a player leaves the server and returns within 5 min - they are not in the group anymore AND they do still have forbidden weapons = ban. But ye, I know what you mean, it's a shame that we can't even have such a minor improvement added
