I fail to see how this wasn't gamechanging:
Mages
* Mage Armor - Now has a new, unique icon.
* Fixed the range for Arcane Missiles when used against large creatures.
Now that mage armor has a unique icon we are able to better discern it against all of those other icons without needing to remember which was which?!
Also, with the number of bosses that are large and the high number of people that played arcane back in vanilla, the second part is arguably even more important than the first.