Oh cool, I wanted to make a thread like this, mainly for future reference since the next games I'm playing will either be Iron Heroes or highly-revamped Iron Heroes. While I kind of detest how magic works in DnD, I'll just ignore for now. (Some of these may be too late for the OP, but eh...)
Check this out:
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Ability Scores: Characters gain 1 point to a stat of their choice every level starting at level 2. There is a limit however: You can only increase a single stat once every 3 levels.
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Likely a player is going to increase their main stat as soon as possible, level 2. Let's say it's STR, which is at 16 at level 1.
Level 2-17
Level 5-18
Level 8-19
Level 11-20
Level 14-21
Level 17-22
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Items that boost a character's stats are still available, but are very rare and are never above +2 or +3 even at the higher level. A Fighter is likely to have one or two magical equip items(not counting armor or weapons), neither boosting the same stats.
Weapons: Magical weapons are changed a great deal. A weapon's worth is pretty much split into: Material, craftsmanship, and (rare) magical effects.
Material: +1 to +5 bonuses are now based on what material the weapon is made of. +0 would be the common Iron, +1 would be something like Steel, and +5 would be some super strong and rare metal. Er, or wood for staves and stuff. Masterwork is still required for +1 and up, let's just say because those materials are harder to work with. Requires revamping of older material rules.
Quality: Aside from "Masterwork", quality is shown by the more 'physical' bonuses that can be applied to weapons. Defending, Distance, Keen, Merciful, Ki Focus, Mighty Cleave, Returning, Speed, Throwing, Vorpal, and Wounding from the DMG would fit on this list (some of them might need a roleplaying twist).
Magical: Some items are blessed with magic, but these are especially rare. All weapons of this type have "Light Generation". All of the "Elemental"/"Alignment" bonus damage effects and their burst counterparts, Bane, Brilliant Energy, Dancing, Disruption, Ghost Touch, Seeking, Spell Storing, and Vicious from the DMG would fit on this list.
In addition, Poisons should become more popular in use and won't be consider evil and won't be against the Paladin code if the poison is the type that could prevent killing(like something that puts the enemy to sleep after one hit).
Armor: Most important change would be armor as DR, just as it is in Iron Heroes(roll it). This DR does most magic, unless the material its made out of states otherwise. For example, most metal armor would be DR/Electricity and Cold. Wood based armor would be DR/Fire and Acid. Just like above, Materials represents basic +# bonuses, Quality represents "physical" special bonuses, and Magical represents "not-so-possible" special bonuses. When attacked with a weapon with a higher +# bonus, subtract that number away from the DR roll.
Defense Bonus: Imo required for anyone using "Armor as DR"
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Feats: A character gains a feat every level. A character can sacrifice a feat for 6 skill points.
Fighter: Skill points every level is 4+INT. Tumble, Listen, Spot, Escape Artist, Bluff, and Sense Motive become class skills. [I know not related really at all, but I just had to squeeze it in because I fear of balancing effects with feats every level]
Health: At level 1, instead of getting Full HP+Con Mod, players get Full HP+1/2 of Con. Every level after, just like Iron Heroes, they get half their hit die + roll other half. Wizards and Sorcerer's Hit die are boosted up to d6, Rogue and Bard hit die are boosted up to d8, and Cleric and Druid hit die are lowered to d6. The feat "Toughness" becomes 3 HP+# of hie die and requires Con 13 to take.
Saving Throws: Will saves are based on CHR instead of WIS.
Natural Magic Resistance: Every character gains a natural DR against all magical effects that deal direct damage. This is equal to their WIS modifier + 1/4 of level. When faced with a death-spell, they add this to their saving throw. This stacks and has no effect on "Spell Resistance". This stacks with armor DR.
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