It seems that most weapon type perks scale very poorly, except maces. Swords' Bladesman does critical damage, which is based off of base damage, so it does little (relatively) once you start upgrading. Axes' Hack and Slash gives bleeding, but that's fixed to a fairly small number.

Maces' Bonebreaker, on the other hand, ignores armor (-25/50/75%). Armor reduces the damage of a physical attack by a percentage. Therefore, Bonebreaker seems to scale by providing a percentage improvement to damage.

But I have no idea what enemy defense/armor ratings look like. Anybody know of a good resource for this?

Enemies hardly have any AR. The ones that do have a very low AR, like 50 or something.

If that's the case, and if armor is calculated the same way as it is for builds, then 50 AC is only about a 6% reduction in damage. With 3 perks in Bonebreaker, you'll do about 4.5% more damage.....lame.

Well, well balanced, or though out, gameplay mechanics are not one of BGS' strengths. Like the killcams (aka Synch-kills) that in case of arrows are neither synchronized nor killing

Gargoyles have an armor rating of 240, but you'll be hard pressed to ever fight more than two handfuls of them. The weapon specialization perks are pretty much junk.

Whixh is why is just better to avoid the 0/3 specialization perks on both One and Two Handed.

Does anybody have a good resource for enemy stats (particularly defense)? And is this changed by difficulty setting at all?

http://www.uesp.net/wiki/Skyrim:Creatures

NPCs AR is effected by their equipment. A bandit chief in Steel Plate or Nordic Carved might have a semi-decent AR, for example.

AR is not effected by difficulty setting. It only effects your damage done and damage taken, nothing else.

i thought the dmg stayed the same and their health was increased at higher diff.

I believe it worked like that in the old games. They improved it for Skyrim. By keeping it practically the same Well, at least they didn't cut the difficulty setting. Yet

I was looking at the uesp site, buy it doesn't seem to list the AC outright.

^ Are you on PC? If so, you can find the armor values through the console.

getavinfo damageresist, to find the armor rating

getavinfo lightarmor or heavyarmor, to find the NPCs skill rating.

Then use the formula on the armor page http://uesp.net/wiki/Skyrim:Armor. Note the increased skill coefficient of NPCs.