I think anything that doesn't have the same affect on every player should be removed.
Such as rain, fog, orange fog(?),night etc. These things vary depending on the time you join the server, it's especially critical in long Strategus battles. For example the last Strategus battle i joined which was a year ago (bad joke sorry) i had orange fog for about first 45 minutes of the battle, when i relogged to server the fog was gone and the sun was shining once more which gave me unfair advantage, which i paid in return by playing even more terrible.