light and heavy amours are way too similar (in oblivion at least). we should also include medium armour for the greatly expanded gap between light and heavy

in athletics
heavy armour tires the player much more than light or medium. the athletics and armour skill should come together to dictate how much heavy armour drains extra fatigue (most of this comes from the armour skill, but athletics is still important
medium armour should be only half as burdened, and light around a fifth.

in acrobatics....
if we still have acrobatics as a "how high can you jump" system, and you are wearing a full set of heavy armour, imagine every point of heavy armour that you DONT have chiping away at your acrobatics skill (if you had 50 heavy armour and 50 acrobatics, you cant jump, if you had 100 heavy armour and 50 acrobatics, you would still jump like you have 50 acrobatics,with extra weight) not to mention your weight having a negative effect on the hight of your jump. medium and light armour should also do this, but with multipliers (if you have 50 agility and 50 medium armour- then you would still be ok to jump due to medium only having 0.xx of the negative effect that medium has)

of course, this is providing you have the full suit of an armour

if bethesda lets you do more with acrobatics (vaulting, climbing ledges, running up walls, rolling etc) then heavier armour should also reflect this. whilst a journeyman may be able to run up a wall to attempt to grab a ledge- you realy have to have 90 heavy armour+ 90 acrobatics to do it with anything heavy.

in short (because i am not good at explaining things in detail via forums)
heavy armour should involk a massive penalty upon acrobatics
medium armour should invoke a penalty upon acrobatics, but still allowing acrobatics to be done
light armour should add a very slight penalty to acrobatics



marksman
heavy armour should effect bows, especialy arm armour (gauntlets, and pauldrons if we are lucky) crossbows (if we are lucky) should not have a massive accuracy decrease, but might be reloaded slower. throwing weapons should be significantly harder in heavy armour



also
heavier heavy armour should render a user imobile if they have very low skill in it.
heavy armour should often weigh more than 6 times that of their light equivalent


you may think i just want to bag heavy armour, but i don't

the best set of light armour may take 3 hits from the best weapon
the best set of medium armour may take 5
the best set should take 10


also, heavy armour should sometimes completely negate shortswords and other blades that use speed rather than strength (criticals should still pack a punch

There are 2 ways to critique this idea. Gameplay mechanics -- approaching the subject only concerned with what affects 'fun' and physic -- the realworld logic behind your idea.

Gameplay: So far all you have done is add penalties to other skills for using Heavy armor, and the only pro seems to be "add more damage absorption". If you want to penalize what appears to be mostly thief classes for heavy, you shouldn't stop there, penalize everything -- basically add negative luck for having heavy. otherwise, you run into balance issues. if you penalize marksmanship, then shouldn't you also penalize the other combat styles (swd, axe, h2h)? otherwise this makes no sense, how would you NOT be penalized for these?
Furthermore, you seem to add Medium simply because "more is better" which is not necessarily true. There were reasons Medium was taken out (we might not agree with those reasons but they were still valid reasons) and your adding it without addressing those reasons. Essentially why do we need another skill that is just like other skills?

Physics: What are you basing these penalties on? There are NUMEROUS sources indicating that even the heaviest plate armors were not THAT encumbering. 40-60lbs. spread over the entire body would not slow you down much unless you had strength of a child. Modern soldiers can run, jump, do obstacle courses, and sprint, with loads up to seventy pounds that AREN'T spread out over the entire body. There is plenty of empirical evidence thanks to our renaissance fair geeks friends that show a fully armored man can maneuver quite impressively in combat situations.
http://www.youtube.com/watch?v=6aqRkxTjV1c is choreographed, not a real fight. I can't say that is real (read full thickness) armor, but even so, you can bet these guys aren't soldiers (read in the best of shape). These people aren't particularly 'skilled' in heavy armor (knights training was pretty thorough, not a hobby). Notice the hammer is more encumbering than the armor simply because its awkward? I see no reason that it should be much more difficult to jump because the weight is disperse across my body than if it was in my backpack (why should Heavy armor reduce acrobatics more than simply encumbrance?) and the only reasons heavy armor would influence archery at all is 1) some gauntlets (especially the 'mitten' type) might make it hard to grip the arrow and 2) the helmet visor (if present) may reduce how well you can see your target. If anything we should REMOVE armor as a skill and 'fix' the balance issue (noobs in plate being almost unbeatable) with reduction in the prominence of high end armor. Plate is expensive, chain is expensive, every goon you meet shouldn't have the access to the best available (read "same as player's level"). Say finding the material (ebony, deadric, steel (steel is iron + carbon, so finding "raw" steel in the ground shouldn't happen)) is "easy" enough, but you need to find a smith work the metal and be able to hire him to custom fit a suit to your frame. And a smith that know the secrets of ebony working wouldn't be cheap. or you could just go assassinate a noble, loot the gear and hope your a good enough sneak not to start the whole county on a manhunt to hang you. I think that is "difference" enough between light (read accessible) and heavy (read "Fing awesome" ) gear.

Put them in a full daedric suit and see how well that goes...

In my opinion deadric should be lighter (less dense at least) but stronger than steel. Why would you think heavier = better. Weight is the disadvantage, ergo the best armor is the one that provides the best protection per lb.

Uhm, that would make daedric go into light armor?

Just because daedric isn't the heaviest doesn't mean it would have to be light armor. Steel offers more protection than Iron, but generally weighs close to the same. Should Steel be light armor because it offers more protection but weighs the same as a lower class of heavy armor?

um NO. Deadric is heavy armor (if we use the heavy/light skill set) what I mean is that deadric (the material) should be lighter (lightER) than steel. I don't recommend making it light armor skill dependent. If you make a steel briastplate and an iron briastplate to have the same resistance (same level of protection) then the iron briastplate would be much heavier (relatively speaking) because steel is stronger and more flexible, you could get the same out of it with less material, ergo steel is better. The same logic could be applied to dwarfish steel, orcish steel, ebony, and deadric. ofc nothing is stopping you from making a steel briastplate that weights the same (or more) as other iron briastplates and the Devs should take that into consideration.