I seem to remember it did in OB. IF they took it out in Skyrim I think that was a mistake.

No reduction from using heavy armor :shakehead:

In OB the effectiveness of a spell was reduced when wearing armor of any sort that you are not skilled with. No effect on Magicka and it had a minor effect overall, I don't think it ever went under 90%.

No it went WAY under 90%, it was all dependent on your skills as to how much, if I recall it went down to like 60%, perhaps even lower with a full set of heavy armor and no real stats.

nope. absolutely no reason to not use armor. movement penalties i guess, mages seem to need to do alot of running away to succeed in skyrim, but the steed stone solves that.