The information is only implied, I think.
Basically, magical items grant you the following that is "cruicial" for your character:
- Attack Bonus (Weapon & Implements)
- Defense Bonus ("Neck" Slot)
- AC Bonus (Armor)
- Damage Bonus (Weapon & Implements)
Look at the magical item levels. Basically, the game excepts something like
Level 1-5: +1 to attack, +1 to damage, +1d6 to critical damage; +1 to AC, Defense
Level 6-10: +2 to attack, +2 to damage, +2d6 to critical damage; +2 to AC, Defense
Level 11-15: +3 to attack, +3 to damage, +3d6 to critical damage; +3 to AC, Defense
Level 16-20: +4 to attack, +4 to damage, +4d6 to critical damage; +4 to AC, Defense
Level 21-25: +5 to attack, +5 to damage, +5d6 to critical damage; +5 to AC, Defense
Level 26+: +6 to attack, +6 to damage, +6d6 to critical damage; +6 to AC, Defense
Actually, these numbers above are not entirely accurate. Masterwork Items are not figured into this. If you want to do this, Light Armor grants another +1 at paragon and +2 at epic tier, and Heavy Armor +2 at paragon and +4 at epic tier. With the items from Adventures Vault, similar values apply for the defenses.
Basically, the magic item system creates a "sub-tier" for every 5 levels. You could just grant these bonuses, maybe in a staggered way to create a "smooth" progression. (Level 2: Attack/Damage Bonus; Level 3: AC Bonus; Level 4: Defense Bonus)
Alternatively, You could make them "training bonuses". If you used an item (armor, weapon or implement) for at least one day of adventuring, you get this bonus, otherwise you don't.
A further aspect you might want to consider is: "What happens with magical daily item uses?" They go up by tier. Most daily items powers are similar as powerful as an extra encounter power (if they are activated "on impact", they make an at-will equivalent to an encounter power, if they grant their own attack, the attack is similar to an encounter power). Best example are the Wands. You could turn this into a "recharge encounter power" mechanic.
Example:
"Heroic Effort": Once per day as a minor action, a character can recover an encounter power he already used this encounter. At Paragon Tier, a character can do this twice, and at Epic tier, he can do it three times. For every milestone, a character can recover one additional encounter power.
If you want to keep magic classes, but remove their reliance on magical items, remove the magical at-wills and replace them with "martial" abilities. You could also replace the heroic tier encounter powers with martial abilities.
A Wizard might get a special Crossbow Attack (Using INT vs AC, deals 1[W]+INT damage, and the target takes a -2 penalty to defense) or a Staff attack (Using INT vs AC, deals 1[W]+INT damage, and the target is slowed.).
A Cleric just uses the "non-Laser Cleric" powers.
The regular At-Wills become "free" encounter powers.
At Paragon Tier, Arcane and Divine heroes can gain access to their first Magical At-Will, retraining one of the at-will-turned-encounter power to become an at-will power (their old at-will power might turn into an encounter power). At Epic Tier, they can retrain the second one.
