A couple of these in other threads, but why not....
1) Soul Gem Sockets - Enchanted weapons can have sockets on them for soul gems. Number of sockets and quality of gems they'll take determined by quality of the item in question. Upon using all charges on a weapon, a socketed soul gem will automatically recharge the item. If there are no soul gems socketed at the time, the standard "out of charges" message appears.
2) No God Mode - Make sure the core game engine doesn't allow for crafting or enchanting anything that makes players invincible (ie. 100% Chameleon). If we want to do that with command line codes or mods, that's what they're there for.
3) Randomize Enchantment Effects - Player-made items should not always produce the exact same effect. When making an item, a range of possible values can result whenever the item is constructed. Also, perhaps include a small chance to make a superior quality item, where the final numerical values are beyond the normal capabilities of the components used. This could add an element of suspense to crafting that could make it quite fun. Of course, you run the risk of people just reloading a save until they get a desired effect, but still... kind of interesting.
4) Realistic Fights - The current trailer seems like they're addressing this, but just to point it out.... The fighting in Oblivion wasn't bad, but the lack of physical damage showing on our enemies (or ourselves) made it seem to an onlooker as if the foe just died of a heartattack ones we finally hacked down the last bits of their health. Realistic facial reactions, bodily movements, hit effects, and damage/blood graphics would go a LONG way to making combat more enjoyable.
I'm sure I'll think of more... just got on these boards today.