There's a number of ways imbuing COULD work and we really don't have enough information to judge the design decisions for imbuing yet.
I think the overall goal of the imbuing system is to make all loot have some value simultaneously. Instead of making item drops immediately valuable (buffing the intensity of loot), I think they have chosen to allow you to turn those mediocre items into magical resources through this imbuing system.
So basically, when you get an item with a high intensity mods but the wrong mods you can unravel that item and hope you get a mod resource for one of the high intensity mods. Up to this point my deduction has covered one of the THREE things that the devs have said that imbuing does. The SA site says imbuing is the art of imbuing, enhancing and unraveling items. I just described how I think unraveling will work (randomly giving you a resource for one of the mods on the item you unraveled).
I think enhancing will work a lot like enchanting does in WoW. Basically, you can use your mod resources you got from unraveling items to attempt to add or possibly enhance a mod on an existing item. I think we will be limited to adding one mod to an item at a time and I think the mods we add could possibly have a lifecycle (their potency could decay over time or use).
It's possible that enhancing an item will only give you a portion of the total mod potency on the mod resource you attempt to apply. I think a good design for enhancing would only let you add one new mod to an item and only allow you to add that mod if the total mods on the item is < 4. In other words you would only be able to have a max of 5 mods on an item. You could also enhance existing mods using mod resorces of a higher potency level than the current potency level on the item you are enhancing.
Successful enhancing would increase the intensity of the mod you enhanced (whether added or buffed) by half the difference between the intensity of your mod resource and the intensity of the mod on your item (minimum of 1). The higher the total intensity of all mods on your item, the more likely you would fail the enhancement.
For Example, say you have HCI 10 (66% intensity) on an item and successfully enhance with an HCI 15 (100% intensity) resource. The system would look at the difference in intensity of 100% and 66% (34% difference) and divide by 2 (17%). This calculated value would be then added to the intensity of your mod, making it an 83% intensity mod. All this math would happen behind the scenes, but the end result would be that your HCI on your weapon would increase from 10 to 12. The only critical thing to watch out for in the math would be to make sure that the system knows that enhancing with a mod resource will increase the intensity. People would get grumpy if they enhanced their 10 HCI down to a 9 because of rounding
Another example... Say you have a weapon with 4 mods and you want to add HCI to the weapon using your 100% intensity HCI mod resource. Let's assume you succeed at enhancing the item. You would get half the intensity (rounded down) of the mod you applied, so you would have 7% HCI on your weapon after successfully applying the mod. You can then enhance that mod later by getting more HCI resources and successfully enhancing the mod furhter.
That leaves imbuing... I think imbuing will either be the ability to create new items with the mods you want (using mod resources) or it could be that imbuing could be just the ability to add mods to items (which was part of my description of enhancing). If imbuing is the ability to apply the full intensity of mods to an item, those items will have to have a forced life cycle.
IMO, some imbuing abilities should consume items and others should just consume resources. Unraveling should consume the item you're unraveling and give you a random mod resource. Imbuing should consume the mod resource whether you succeed or fail. Enhancing should also consume the mod resource whether you succeed or fail.
The only balancing factors as I see it will be to make sure that adding and enhancing mods on items becomes progressively harder (requiring higher imbuing skill and having higher fail rate) to the point that it restricts players from "capping out" full suits.
Another possibility is that mods that have been added on to items have a life cycle. In other words they decay over time, which requires you to get them re-applied in order to keep the item in peak form.