After quests have been completed, or during the course of completing them, my Player Characters might pick up new armor or weapons that I've put placeholders in for, but eventually I reach a point where I need to create stats for these custom weapons or armor (that are not based on equipment in the various published books). What is the best way to manage how much damage these weapons inflict, or how much extra protection the armor gives the player?
[RPG] the best way to create custom weapons and armor for your PCs
dnd-4eequipmentgm-techniquesmagic-items
Related Solutions
You're misusing the guidelines.
First, let's take a look at what the Pathfinder Magic Item Gold Piece Values section has to say on this issue. Turns out, it is specifically addressed.
The correct way to price an item is by comparing its abilities to similar items (see Magic Item Gold Piece Values), and only if there are no similar items should you use the pricing formulas to determine an approximate price for the item. If you discover a loophole that allows an item to have an ability for a much lower price than is given for a comparable item, the GM should require using the price of the item, as that is the standard cost for such an effect. Most of these loopholes stem from trying to get unlimited uses per day of a spell effect from the "command word" or "use-activated or continuous" lines of Table: Estimating Magic Item Gold Piece Values.
Emphasis mine. It then goes on to take Mage Armor as an example of this:
Patrick's wizard wants to create bracers with a continuous mage armor ability, granting the wearer a +4 armor bonus to AC. The formula indicates this would cost 2,000 gp (spell level 1, caster level 1). Jessica reminds him that bracers of armor +4 are priced at 16,000 gp and Patrick's bracers should have that price as well. Patrick agrees, and because he only has 2,000 gp to spend, he decides to spend 1,000 gp of that to craft bracers of armor +1 using the standard bracer prices.
So yes, your Amulet of Mage Armor and Shield is a textbook example of the guidelines gone bad.
This is understandable. The guidelines are famously weak, often breaking with casual use, as you have encountered. This precise case, however, was anticipated and addressed.
Use wish lists.
Here's the thing, you've run into the bane of the 4e DM's existence. This is a problem I think everyone who has been a DM for 4e has run into, and there are precious few good solutions to it. Here's how I'd recommend doing it:
Have every player create a wish list, have it include 10 common magic items, 4 uncommon magic items, and 1 rare item.
Make a card for each one.
If you want to award a specific item in a treasure parcel, great! if not, then draw them randomly from the deck you made for the given rarity of the parcel. Use the parcel generation system from the RC and award 10 per level.
Stick to the item rarity rules for sales. They can only purchase common items except in certain instances (I know in our game, our DM allows us to purchase uncommon items, but they are often hard to find so there is a time constraint/delay).
If they want specific items badly (especially rare items), make them side quests! Whether it's just the player in question or the whole party is after a specific set of items or whatever, these can be important character developments and make your whole table more invested in the items they are receiving.
The other option here is to scrap the item rarity update, make all magic items the same rarity and enforce the original 4e rules on daily item powers (those are found in the PHB, the long story short is that you can only use 1 item daily power per milestone period).
I'd definitely recommend you go to a wish list and treasure parcel system over returning to the pre-rarity era though.
This can be a bit of a maintenance nightmare for the players (though it sounds like your players are pretty on top of things as far as item selection goes). If they can't be bothered to keep up wish lists, then I'd award coupons for magic items for them to pick out. (a Level X rare item, a Level Y uncommon neckslot item, etc). Let your players decide who gets the item each time one is awarded.
As far as balance goes, make sure you aren't awarding or making available for sale items of too high a level (+4 I believe is what the treasure parcels use). This should keep the math good for your characters. And let's be honest here, 4e characters, especially paragon and epic tier characters are hugely powerful. They are going to chew through a lot of encounters fairly easily, though hopefully not too many of them. Item rarity enforcement should help a bit with keeping the most powerful combos at bay though.
Best Answer
In terms of enhancement bonus, players should start finding +1 gear almost immediately, +2 gear around level 5, +3 gear around level 10, +4 gear around level 15, +5 gear around level 20, and +6 gear around level 25. Note that any armor that has a high enough enhancement bonus to be masterwork should always be the best kind of masterwork allowed for its enhancement bonus. Masterwork armor is a math fix for the way player defenses tend to lag compared to monster attacks as party level increases; it is not something special that players should have to work to get.
In terms of special abilities, weapons that give a conditional bonus to damage (against enemies of a specific type, against enemies larger than you, on your attacks with a specific keyword, etc) usually give an item bonus equal to their enhancement bonus; weapons with an unconditional damage bonus are very powerful.
Armor and neck items that directly give extra protection are unusual and rather powerful; most give a daily item power, a skill bonus equal to the item's enhancement bonus, or both. If they do give a protective boost, the most common is a +2 bonus to 1 or 2 defenses when a common condition is met (you shifted this turn, you're a druid in beast form, etc) or against certain kinds of attacks (close attacks, ranged attacks from 5+ squares away, etc).
Remember: damage bonuses should go up as the party gains levels, defense & attack bonuses should not (except for enhancement bonuses).
A good item gives one, maybe two of: a very small always-on bonus, a moderate conditional bonus to damage/attack/defense, a moderate always-on boost to initiative or 2 skills, a daily power equivalent to an encounter utility power or capable of making an encounter power closer to a daily power in strength, or an encounter power equivalent to an at-will utility power.
If you want an more powerful item and/or an item with lots of roleplay significance, take a look at artifacts (which unfortunately are spread around in a variety of books) for some examples and ideas.
If you have DDI, an easy way to estimate how good items should be is to look through the compendium and see what magical enchantments already exist for that item at that level.