Really don't see how that can be comprehended any other way than a damage nerf.
W/M did need it, though. It's not a terribly huge decrease, and they should still be near the top for DPS. They also fixed the elite killing warmages, too, which is nice.
No, see Warmage's have a lvl 45 elite skill called Electric attack which puts electricity into your weapon and is very similar to the lvl 60 elite, but just not as much damage. They also have a lvl 50 elite skill which puts fire into your weapon and is similar to the lvl 45. The problem is, you couldn't activate both of these buffs at the same time. I think what the level 60 elite skill does is allows you to combine both of the powers, but each are reduced by 25%. So instead of giving you double what the lvl 50 elite skill gives you, it only gives you 150% of what the level 50 elite skill gives you.
I am a warmage and even before the patch, the lvl 60 elite skill did quite a lot of damage, but not enough to be double what the lvl 50 elite skill did. I think what they did in the patch, if you read it, is just change the description to make it more clear, but they didn't actually change the amount of damage it did. Before, it was unclear just how much additional damage the lvl 60 elite skill provided over the level 45 and level 50 elites, but now this updated description tells you it is 150%. This is just my interpretation of it and I could be wrong though.