... into making a spell that lets you dissolve another magic item, use it's magic essence, and more cheaply enchant a different item.
I give you, The Rope of Transference (because despite my stinginess, in my 13 year campaign, they got a LOT of magic they outgrew, or were beyond when they got it):
The Rope of Transference (Constant Item, Min Research 2 Weeks, DC 40)
Lesser:
Transfer Magic Arms and Armor: Allows Transfer of All Magical Properties of ONE magical weapon or armor of like kind – weapon to weapon, armor to armor, shield to shield, to an unenchanted masterwork item. Takes 10 minutes per “plus”/1000gp value transferred, draws 50% of the normal crafting XP from the user of the rope, and completely devastates the originating magic item. The slagged material can never be used in magic item creation.
Isolated Transfer: Allows the transfer of 1 magical property from a magical weapon or armor to a previously enchanted magical weapon or armor of like kind that is not fully enchanted. Takes 10 minutes per “plus”/1000gp value transferred, draws 75% of the normal crafting XP from the user of the rope, and completely devastates the originating magic item. The slagged material can never be used in magic item creation.
Need: Transference Feat, Min Caster Level 12, 90000gp Unlimited Use
(Costs for per week use, 4: 85000; 3: 80000; 2: 70000; 1: 60000)
Standard:
As Lesser, except Isolated Transfer instead drains from the source item a number of “plusses” equal to the transferred power +1. These drained plusses are lost randomly. If the source item retains at least a +1 enhancement bonus after the transfer it retains it’s basic magical nature. An item which cannot pay the “plus” cost, is devastated as per a Lesser Rope. Only one power may be transferred at a time, but so long as the source item remains magical, the rope may be used on it to transfer additional powers. Furthermore, the transfer costs twice the original power’s XP cost to craft from the user, and takes 30 minutes per plus transferred.
Need: Transference Feat, Min Caster Level 15, 125000gp Unlimited Use
(Costs for per week use, 4: 115000; 3: 105000; 2: 95000; 1: 90000)
Greater:
As Standard, except as follows: Isolated Transfer drains plusses equal to the transferred power, and costs 5 times the original crafting XP.
Wondrous Transfer: The rope may be used in a fashion similar to Transfer Magic Arms and Armor with wearable non-armor constant items (garments, rings, etc). This takes 30 minutes per 1000gp value of the originating item, and costs the original XP crafting cost if the target item is metaphysically/thaumaturgically related to the magic in question, or 10 times if it is not.
Need: Transference Feat, Min Caster Level 18, 275000gp Unlimited Use
(Costs for per week use, 4: 260000; 3: 245000; 2: 225000; 1: 200000)
Grand:
As Greater, but gains the ability of Wondrous Isolated Transfer, allowing transfer of 1 power to a previously enchanted non-armor wearable constant item, destroying the source item, taking 1 hour per 1000gp value of the source item, and costing XP equal to 5 times the original crafting XP for thaumaturgically related items, and 20 times for non-related items.
Need: Transference Feat, Min Caster Level 20, 400000gp Unlimited Use
(Costs for per week use, 4: 375000; 3: 325000; 2: 300000; 1: 275000)
They didn't use it as often as you might think, but the times they did use it made for some very excellent armor and weapons...