Hey,
It wasn't Centre-weighted I was thinking of either. I'd never heard of what I described, but I read someone on a forum (here or CR) say something like it, that in some combination of metering modes and AF points, all in-focus points (no matter where they are) will be weighted more heavily when metering a scene.
And i'm pretty sure they were talking about the 7D, but i've just skimmed through the manual and couldn't find it (nor in the 5D3 manual). So maybe they were talking about the 1DX, or i dreamed it (yes, that's possible)...