Improving Named magic items

[Manyasone]

I'm curious as to other DM's handle this...normally there are rules that state if you improve a magic item you reduce the cost with the current cost of the item.
So far, so clear. Named magic items, in this case 'Celestial Armor' has a +3 enhancement bonus and some other bits. I can't really think of a reason why they shouldn't be able to improve the enhancement bonus. Other shenanigans are always on a case by case basis at my table...I care about the Rules but also about the Lore.

Ideas? Suggestions?

[Thurbane]

I've asked this exact question myself before - it's generally a bit of a grey area.

In most cases, it shouldn't be an issue. But some items are a bit poorly defined, so modifying them, changing the material they are made from or adding abilities or bonuses sometimes causes glitchy cost calculations.

The RAW is fairly silent on if this is allowed or not.

[Necrov]

I'm curious as to other DM's handle this...normally there are rules that state if you improve a magic item you reduce the cost with the current cost of the item.
So far, so clear. Named magic items, in this case 'Celestial Armor' has a +3 enhancement bonus and some other bits. I can't really think of a reason why they shouldn't be able to improve the enhancement bonus. Other shenanigans are always on a case by case basis at my table...I care about the Rules but also about the Lore.

Ideas? Suggestions?

Why would changing the enhancement bonus or adding any extra properties be any different than with a regular +3 chain shirt, or whatever. There is a cost, and a time taken for the work... which if I recall is one day per 1000gold the enchantment costs. So far as I can see, it being a named magic item makes no real difference. Work out what the current enhancement of the weapon is (essentially what the enhancement values of the other properties on the weapon are) and then there's a table which will tell you how much the next upgrade (whatever form that takes) will cost in the DMG, I believe.

[Telonius]

I treat the DMG items as things that are generally available (assuming the settlement is big enough to meet the GP cost). If they want something other than the basics, they're going to have to wait until someone (either a PC or an NPC) can make a custom item. You can certainly add on to an existing magic item, using the regular Adding New Abilities (http://www.d20srd.org/srd/magicItems/creatingMagicItems.htm#addingNewAbilities) rules. They even give an example of adding the powers of a specific named item (a Ring of Invisibility) to a Ring of Protection +2.

EDIT: I believe Magic Item Compendium expands on the rules a bit and gives more examples, but I'm away from my books.

[Thurbane]

Some of them are quite hard to reverse engineer a price from - the pricing of Shifter's Sorrow (force shapechanger back to original form ability) still gives me headaches, as I'd love to be able to put that item power on something other than a two-bladed sword.

[Jay R]

It's a more complex item. I would let you improve the Celestial Armor only if you have the abilities necessary to make Celestial armor. In that case, I have no problem with you enhancing it.