[SixOfSpades]

That depends on the enchantment and the item type. Suppose there was a pair of Boots named Nimbletoes, that made the wearer uncannily quick on their feet, granting a -1 AC bonus (additional -1 against missiles), +2 to movement rate and -1 to Speed Factor, and +1 to Charisma when worn by Bards (dancing). It would be ludricrous to make an item upgrade that transferred these enchantments to a Halberd, or a Shield. But combining them with the Boots of Avoidance, or moving some of Nimbletoes' properties to, say, a Cloak, Ring, or Girdle, might make some sense.

I've no objection to the idea that enchantments can be "lifted out of" one item and transferred to another, provided that the exchange fits a good, solid theme and is sufficiently costly--and there has been a good attempt to include appropriate quest items.

It always gets trickier when combining different types of items: It's obvious what happens when you melt two Rings together, or when you use a stack of Arrows to upgrade your Bow, but what happens when you add items of 2 completely unlike types? Two-Handed Sword + Cloak = ??? You've got to make sure it makes sense--Rings bonded onto a pair of Gloves is one upgrade that sounds perfectly logical.